Concentric tubular centrifuge

ABSTRACT

A two-tube centrifuge separates light material and heavy material from an input mixture. A hollow drive shaft rotates a central body member about an axis of rotation. Two hollow arm assemblies, each having circular cross-section, are mounted on diametrically opposite sides of the central body. Each arm assembly includes an outer housing tube, an intermediate tube, and an inner tube that is longer than the intermediate tube. An end cap having a removable plug is mounted on the outer end of the housing-tube of each arm assembly. The inner ends of all three tubes are mechanically interlocked in a manner to cantilever mount the inner and intermediate tubes to the central-body with their outer ends spaced from the internal surface of the end cap. An input-mixture path extends through the hollow drive shaft, through the central-body, and into a cylindrical space between the inner and intermediate tubes of each arm assembly. A heavy material exit path extends from the inner tube, through the central body, and into an exit cone that lies diametrically opposite the drive shaft and whose axis is coincident with the axis of rotation. A light material exit path extends from a cylindrical space between the inner and intermediate tubes, through the central-body, and through a wall of the exit cone. The inner tube of each arm assembly includes an auger. An electric motor drives the drive shaft. A hydraulic motor drives the auger. An oxidation reactor in a centrifuge for decanting lighter material from heavier material from a mixture of initial material and to perform an oxidation reaction process on the heavier material.

CROSS-REFERENCE TO RELATED APPLICATIONS AND U.S. PATENTS

[0001] This application is a divisional patent application of copendingU.S. patent application Ser. No. 09/828,296, filed Apr. 6, 2001,entitled CONCENTRIC TUBULAR CENTRIFUGE; which is a continuation-in-partof copending U.S. patent application Ser. No. 09/707,430 filed Nov. 6,2000, entitled CONCENTRIC TUBULAR CENTRIFUGE; which is a continuation ofU.S. patent application Ser. No. 09/298,272 filed Apr. 23, 1999,entitled CONCENTRIC TUBULAR CENTRIFUGE, now U.S. Pat. No. 6,142,924;which is in turn a continuation application of U.S. patent applicationSer. No. 08/950,377 filed Oct. 14, 1997, entitled CONCENTRIC TUBULARCENTRIFUGE, now U.S. Pat. No. 5,944,648; which claims priority to bothU.S. Provisional Application Serial No. 60/215,499, filed Jun. 30, 2000,entitled CONCENTRIC TUBULAR CENTRIFUGE, and U.S. Provisional ApplicationSerial No. 60/195,686, filed Apr. 7, 2000, entitled CENTRIFUGALOXIDATION REACTOR; all of which are incorporated herein by reference asif fully set forth herein.

FIELD OF THE INVENTION

[0002] This invention relates to centrifuges and more particularly tocentrifuges used as oxidation reactors.

BACKGROUND OF THE INVENTION

[0003] Centrifuge technology has long been used to separate mixtures ofmaterials into their heavy and light components. Centrifuge technologyis useful in many fields, including, but not limited to, medical,industrial, and public service sectors, all within various specificapplications where separation technology is beneficial.

[0004] The effectiveness of presently known centrifuge technology isdependent upon factors such as the magnitude of the separating force(centrifugal force) that is generated by the centrifuge and theresidence time during which the material to be separated is subjected tothe separating force. Virtually all centrifuges rely on some type ofrotary motion to generate a separating force. Thus, the magnitude of theseparating force that is generated depends on the size (moment arm) ofthe centrifuge and the speed at which the centrifuge rotates. Togenerate a given magnitude of separating force, a small-size centrifugemust be driven at higher revolutions per minute (RPM) than is requiredof a large-size centrifuge.

[0005] The residence time during which the material to be separated issubjected to the separating force depends upon the flow-path of thematerial through the centrifuge. This flow-path is defined by theinternal structure of the centrifuge, and its length is sometimeslimited by the type of centrifuge. Typically, the longer the residencetime of a material under a given separation force, the better theseparation of the light material from heavy material.

[0006] Existing centrifuge technology is limited in its ability to allowa change to be made in the separation force and/or in the residencetime.

[0007] While existing relatively large-size centrifuge technology iscapable of handling relatively large inflow rates, such as 100 gallonsper minute (GPM), it is not conducive to portable use in aself-contained unit. Such large size centrifuge structures are difficultto transport, require frequent skilled maintenance, and often do notallow simple modification of the separation force and/or the residencetime in order to adjust the centrifuge as input material conditions oroutput material requirements vary.

[0008] In present supercritical oxidation reactors, a complex mechanicalsystem is required for creating the environment necessary to perform thesupercritical oxidation reaction. For instance, in these complex systemssignificant effort is given to controlling the pressure, both increasingthe pressure to that required for the process and then decreasing thepressure to allow waste removal. The associated equipment can beexpensive to build and possibly dangerous to operate. The supercriticalreaction systems presently available typically incorporate several stepsin order to sequentially build up the required pressure and temperatureto adequately perform the supercritical reaction process. These systemsare expensive and have relatively low throughput.

[0009] What is needed in the art is an apparatus to allow the performingof the oxidation reaction, both supercritical and subcritical, which isinexpensive, relatively simple to operate, allows continuous processingof relatively high flow rates, and is easy to maintain and repair.

[0010] It is with the foregoing issues in mind that the centrifuge ofthe present invention was developed.

SUMMARY OF THE INVENTION

[0011] This invention provides a centrifuge having at least one armassembly that rotates in a generally vertical plane and that extendsoutward on a common radius from a generally horizontal axis of rotation(spin axis).

[0012] The present invention pertains to a centrifuge for accepting aninput mixture and for separating a light material that is within themixture from a heavy material that is within the mixture. The centrifugehas a housing having a central member that is rotatable on an axis ofrotation and also has at least one arm assembly used for separation ofthe light material from the heavy material. The housing is constructedsuch that the lower half of the housing can be placed below groundlevel. The arm assembly has an outer tube with a first end operablyconnected to the central member and a closed second end extending awayfrom the central member. The arm assembly has an intermediate tubeoperably connected to the central member that is located within theouter housing. This location defines a first annular flow path betweenthe outer housing and the intermediate tube. The arm assembly also hasan inner tube that is operably connected to the central member that islocated within the intermediate tube. This location with respect to theintermediate tube defines a second annular flow path between theintermediate tube and the inner tube as well as a tubular flow pathwithin the inner tube. An input mixture flow path is provided to receivethe input mixture. This input mixture flow path extends through thedrive shaft, through the housing and is in communication with one of thefirst and second annular flow paths. There is also a light material flowpath communicating with the other of the first and second annular flowpaths and a heavy material flow path communicating with the tubular flowpath.

[0013] According to another aspect of the present invention, the outertube housing is operably connected to the central member by a firstmounting ring. The intermediate tube is operably connected to thecentral member and the first mounting ring by a second mounting ring andthe inner tube is operably connected to the central member and thesecond mounting ring by a third mounting ring. The first mounting ringhas an overhanging portion that overlies a portion of the secondmounting ring, the second mounting ring has an overhanging portion thatoverlies a portion of the third mounting ring.

[0014] A first speed-controllable drive means drives a hollow driveshaft that defines the centrifuge's horizontal axis of rotation. One endof this drive shaft is bolt connected to a central member that rotateson the axis of rotation. The arm assembly is mounted onto this centralmember and is contained within a relatively large annular housing thatis formed generally concentric with the axis of rotation. Thecentrifuge's separation force is a direct function of the speed of thisfirst drive means and this force is varied by varying the speed of themotor. The residence time of the centrifuge is related to the length ofthe arms and the number of cylindrical tubes, which can be changed asdesired.

[0015] The inner tube of each centrifuge arm assembly is a long tubehaving a small diameter. This inner tube may contain an elongatedconveyer screw or auger that aids in the transport of heavy materialradially inward toward the axis of rotation. A flow of heavy materialenters the far end of this inner tube, moves inward toward the centralmember, enters the central member and makes a 90° degree turn in adirection away from the drive shaft, flows into the apex of aheavy-material discharge cone, through the discharge cone, and then intoa small-size annular housing that is formed concentric with the axis ofrotation.

[0016] This heavy material discharge cone extends outward from thecentral member. The horizontal axis of the discharge cone is generallycoincident with the centrifuge's axis of rotation, and the dischargecone is located on the opposite side of the central member from thedrive shaft.

[0017] A second speed-controllable drive means is mounted onto thecentral member, generally coincident with the centrifuge's axis ofrotation. This second drive means is connected to drive the conveyorscrew. Speed-control of this second drive means enables the speed ofconveyor screws to be controlled independent of the speed at which thecentrifuge's arm assemblies are rotated by the first drive means.

[0018] The intermediate tube of the centrifuge arm assembly is of anintermediate length and an intermediate diameter. An input mixture thatis to be separated, and that contains both heavy and light material,flows through the hollow drive shaft and into the central member whereit makes a 90° turn, flows into the inner end of an annular space thatexists between the inner tube and the intermediate tube, and then flowsoutward from the axis of rotation to the outer end of the arm assembly.

[0019] The outer housing of each centrifuge arm assembly has theshortest length and the largest diameter. Light material that has beenseparated from the input mixture flows into the outer end of acylindrical space that exists between the intermediate tube and theouter housing, inward toward the axis of rotation, into the centralmember where it makes a 90° degree turn, through conduits that areformed in a side wall of the heavy material discharge cone, and theninto an intermediate size annular housing that is formed concentric withthe axis of rotation.

[0020] As a feature of the invention, the two centrifuge arm assembliesprovide for selective replacement of components that are within the armassembly(s), and provide for modification of the arm assemblies in orderto change the separation characteristics of the centrifuge. This isachieved by including a removable plug and/or a removable end cap on theend of the outer tube housing.

[0021] According to another aspect of the present invention, a method ofusing a centrifuge to separate a light material that is within an inputmixture from a heavy material that is within the input mixture, while atthe same time independently controlling a speed of rotation of thecentrifuge and a speed of removal of the heavy material from thecentrifuge is provided. The method includes the following steps:providing a first and a second arm assembly aligned on an arm-axis andthat are rotatable in a plane extending generally perpendicular to arotation-axis; providing that each of the arm assemblies includes atubular-housing having a closed outer end, an intermediate tube havingan open outer end, and an inner tube having an open outer end; providingthat the inner tube of each arm assembly is of a given length; providingthat the intermediate tube of each arm assembly is of a length that isless than the given length; providing that an outer end of thetubular-housing of each arm assembly is spaced from the outer end of theintermediate tube and from the outer end of the inner tube; providing aninput mixture flow path that communicates with a cylindrical spacebetween the intermediate tube and the inner tube of each arm assembly;providing a heavy material flow path that communicates with a spacewithin the inner tube of each arm assembly; providing a light materialflow path that communicates with a cylindrical space between theintermediate tube and the tubular-housing of each arm assembly;providing a conveyer screw within the inner tube of each arm assembly;providing a first speed controllable drive means connected to effectrotation of the first and second arm assemblies about the rotation-axis;and providing a second speed controllable drive means connected toeffect rotation of the conveyer screws.

[0022] In an embodiment of the invention, but without limitationthereto, the input mixture to the centrifuge of the invention is awater-containing liquid that is not potable, and the light materialoutput from the centrifuge comprises potable water.

[0023] The present invention includes a novel system and method foroxidizing materials. In both the system and method embodiments, anoxidation reaction is contained within a centrifuge.

[0024] The system for oxidizing materials includes an entry zone, athickening zone, a reaction zone, a cooling zone, and an exit zone. Theentry zone includes a centrifuge influent manifold and beginning portionof a centrifuge arm, the reaction zone encompasses the end portion of acentrifuge arm, the cooling zone is contained in the center channel of acentrifuge arm, and the exit zone includes the centrifuge effluentmanifold. Influent materials are introduced to the system via the entryzone. The influent materials are then thickened in the thickening zonebefore being transported to the reaction zone. In the reaction zone, thematerials are oxidized in an oxidation reaction. The oxidationby-products (effluent) are next cooled in the cooling zone beforeexiting the system via the exit zone.

[0025] The method for oxidizing materials involves passing an influentmaterial through the various system zones (entry zone, thickening zone,reaction zone, cooling zone, and exit zone) described above. In additionto oxidizing the influent materials, lighter fluids present in theinfluent materials may be decanted during the normal operation of thecentrifuge if desired. By controlling the system probe, the volume ofcentrate produced can be controlled.

[0026] The centrifuge can be used as a supercritical oxidation reactoror a subcritical oxidation reactor, depending on the conditions insidethe reactor, as controlled by the user. Given the extreme pressure builtup in the end of each arm of the centrifuge as described herein, the endof each arm can act as the reaction zone for the supercritical oxidationreactor with the proper addition of an oxidant into the system and withthe proper addition of heat to create the ideal reaction zoneparameters.

[0027] The instant centrifuge can be used as an oxidation reactor, bothfor subcritical and supercritical conditions. In this embodiment, thecentrifuge includes a main body having at least one inlet and at leastone outlet and being rotatable about an axis, at least one hollow armextending from said main body, said arm having a distal end and aproximal end, said arm defining at least an interior inlet flow pathcommunicating with and leading from said inlet at said proximal endoutwardly to said distal end, and at least a first exit flow pathleading from said distal end to said proximal end and communicating withsaid outlet, and a heat source at said distal end, and a reactor regionformed at said distal end of said arm.

[0028] In greater detail, the oxidation reactor could also include aflow path for inserting an oxidant into to said reactor region.

[0029] In further detail, the oxidation reactor could also include asecond exit flow path leading to a second outlet, said first exit flowpath for the flow of the incoming material after passing through saidreactor region, and said second exit flow path for liquid separated fromthe incoming material.

[0030] In further embodiments, the oxidation reactor can be suspendedfrom a frame so as to rotate about a vertical axis, and the outlet ofthe oxidation reactor can be positioned in a tank below the frame. Thetank can have liquid, such as water, therein to assist in handling thereaction by-products.

[0031] Other aspects, features and details of the present invention canbe more completely understood by reference to the following detaileddescription of a preferred embodiment, in conjunction with the drawings,and from the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the figures of this application an X-Y-Z coordinate system isshown as an aid to orienting the figures one to another.

[0033]FIG. 1 is a top and right side perspective view of a centrifuge inaccordance with the present invention wherein an input mixture to beseparated enters the centrifuge by way of a hollow drive shaft thatsupports a rotating arm assembly within a large-size andvertical-standing annular housing, this view showing a rectangular frameand frame-mounted electric motor and belt that drive the drive shaft,this view showing an intermediate-size annular housing out of whichlight material flows, and this view showing a small-size annular housingout of which heavy material flows.

[0034]FIG. 2 is a right side plan view of the centrifuge of FIG. 1.

[0035]FIG. 3 is a top and right side perspective view of the rotatingarm assembly that is contained within the relatively large annularhousing of FIG. 1.

[0036]FIG. 4 is a top section view taken along the line 4-4 of FIG. 2,this view showing how the left-hand and belt driven end of the hollowdrive shaft cantilever-supports the centrifuge's rotating arm assemblyby way of two frame-mounted bearings, this view also showing thecentrifuge's input flow path, the flow paths that exist within therotating arm assembly, the light-product output flow path, theheavy-product output flow path, and hydraulic-fluid input and outputflow paths that power a centrally located hydraulic motor that drivestwo heavy-produce output conveyer screws that are within the rotatingarm assembly.

[0037]FIG. 5 is an enlarged section view similar to FIG. 4, this viewbetter showing the construction and arrangement of a centrally locatedand manually removable plug that is contained within a bell-shaped endcap that establishes the outer end of each rotating arm within therotating arm assembly.

[0038]FIGS. 6 and 6A are enlarged section views of the central portionof the centrifuge as shown in FIG. 5, this view better showing theconstruction and arrangement of the base portions of the threeconcentric tubes that are cantilever-supported within each arm of thecentrifuge's rotating arm assembly.

[0039]FIG. 7 is a section view taken on the line 6-6 of FIG. 5, thisview showing four light-product flow paths that supply the light-productoutput to the intermediate-size annular housing shown in FIG. 1.

[0040]FIG. 8 is a section view taken along the line 7-7 of FIG. 7, thisview showing a cross section of the centrifuge's heavy-product outputcone, and this figure also showing two of the four light-product flowpaths of FIG. 7 in greater detail.

[0041]FIG. 9 is a partial section, top and right side perspective viewof the centrifuge, this view also showing two of the four flow paths bywhich the heavy material output flows to the small-size annular housingshown in FIG. 1.

[0042]FIG. 10 is a view similar to FIG. 9 wherein the construction andarrangement of one of the two arms is better seen.

[0043]FIG. 11 is a view that shows how one of the inner ends of the twoheavy material output augers are connected to opposite sides of thecentrally located hydraulic motor.

[0044]FIG. 12 is a view that better shows the snap ring construction ofthe removal plug that is contained within the bell-shaped end cap thatestablishes the outer end of each rotating arm within the rotating armassembly.

[0045]FIG. 13 is a side section diametric view of a centrifuge andcentrifuge arms and reactor zones.

[0046]FIG. 14 is an enlarged view of the sludge thickening and reactionzone portions of the centrifuge arm.

[0047]FIG. 15 is a graph illustrating the pressure in the centrifuge armversus the length of the centrifuge arm.

[0048]FIG. 16 is a graph illustrating the specific volume in thecentrifuge arm versus the length of the centrifuge arm.

[0049]FIG. 17 is a graph illustrating the velocity in the centrifuge armversus the length of the centrifuge arm.

[0050]FIG. 18 is a graph illustrating the temperature in the centrifugearm versus the length of the centrifuge arm.

[0051]FIG. 19 is a representative section of a centrifuge of the presentinvention configured for use as an oxidation reactor, including a heatsource positioned at the distal end of both arms.

[0052]FIG. 20 is a representative section of another embodiment of thepresent invention configured for use as an oxidation reactor.

[0053]FIG. 21 is an enlarged view of one of the arm sections of theoxidation reactor shown in FIG. 20.

[0054]FIG. 22 shows another embodiment of the centrifuge of the presentinvention configured for use as an oxidation reactor, including a framefor suspending the reactor and a tank for receiving the oxidationreaction by-products.

[0055]FIG. 23 is an enlarged view of one of the arms of the oxidationreactor shown in FIG. 22.

[0056]FIG. 24 is an isometric view of the frame and tank structure withthe oxidation reactor suspended therefrom, including the drive motor andthe breaking system.

[0057]FIG. 25 is a flow chart representing the process related toselecting whether or not the oxidation reactor should include an exitflow path for a centrate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0058] This invention will be described relative to the separation of aninput mixture that contains heavy solids and relatively light liquids.However, the invention can be used with virtually any generally liquidinput mixture that contains both heavy and light material, for example amixture of oil and water. Also, the input mixture can be filtered priorto being introduced into the centrifuge of the invention.

[0059] The input mixture can be introduced into the centrifuge by way ofgravity feed or by way of pressure feed as achieved by pumping. Thecentrifuge 10 of the present invention is relatively insensitive to theflow-rate of its input mixture, to the solid content of its inputmixture, and to the volumetric weight of its input mixture.

[0060] FIGS. 1-12 show a centrifuge 10 in accordance with thisinvention. Important features of this invention include, but are notlimited to, a rotating assembly 12, 14 that rotates in a X-Z verticalplane; independent motor-drive of rotating assembly 12, 14 andhorizontally extending conveyer screws or augers 36 that aid in thetransport of heavy material out of centrifuge 10; anend-cap/multiple-bold/interlocking-base construction and arrangement bywhich two concentric tubes 30, 32 and an outer concentric tube-housing34 defining the flow path of the material that can be easilydisassembled/reassembled in order to repair/modify the centrifuge'srotating assembly 12, 14; a wide, cone-shaped, exit path 18 by which theheavy material exits centrifuge 10; and the exit path(s) 20 of thelighter material.

[0061] With particular reference to FIGS. 1 and 4, centrifuge 10 inaccordance with the invention operates to continuously separate largevolumes of an input mixture 16, such as waste water, oil well drillingfluids, etc., that generally consists of a mixture of a light material22 and a heavy material 24. In the operation of centrifuge 10, the inputmixture 16 enters the centrifuge at 26, light material 22 exits thecentrifuge at 104, and heavy material 24 exits the centrifuge at 82.

[0062] Centrifuge 10 includes at least two laterally opposed and axiallyaligned rotating-arms 12 and 14 that extend perpendicularly outwardlyfrom one end 38 of a hollow drive shaft 28. The internal volume of driveshaft 28 carries input mixture 16 from input end 26 to the inner ends ofarm assemblies 12, and 14.

[0063] The opposite end portion 26 of drive shaft 28 into which inputmixture 11 is introduced is bearing-supported by two shaft-bearings 42and 44 that are mounted on and supported by a rectangular frame 46 andits generally centrally located flat plate 48. A relatively largeannular housing 50 is also supported by frame 46. Housing 50 surrounds,protects, and contains the centrifuge's rotating arm assembly 12, 14.

[0064] Drive shaft 28 and its end-supported arm assembly 12, 14 aredriven by an electric motor 52 that is mounted on frame 46. Motor 52 andits drive belt 54 cause drive shaft 28 to continuously rotate in onedirection about a rotational or Y-direction axis 24 that is coincidentwith the center of drive shaft 28. Rotation of drive shaft 28 developsthe centrifugal forces that are necessary for material separation.

[0065] While physical dimensions are not a limitation on the spirit andscope of the invention, centrifuge 10 is relatively large. For example,the total length of rotating arm assembly 12, 14 may be in the range offrom 7 to 8 feet, the diameter of each arm 12, 14 may be in the range offrom 1 foot to 1.5 feet, and the rotational speed of shaft 28 may beabout 3000 revolutions per minute (RPM). In addition, in an embodimentof the invention, but without limitation thereto, the centrifuge's frame46 occupies a horizontal plane, and a lower portion of housing 50 mayextend below ground level.

[0066] With particular reference to FIGS. 4, 5 and 10, each of the twotubular-shaped arms 12, 14 has a generally cylindrical shape and are ofgenerally the same construction. Each of the arms 12, 14 includes acup-shaped end cap 56, an innermost tube 30, an intermediate tube 36 andan outermost tubular housing 34. Seven parallel and radially extendingmetal bolts 58 have their inner ends threaded into a centrally locatedcentral member 60 that is bolt-attached to the end 38 of drive shaft 28.The outer ends of bolts 58 are nut-attached to end cap 56.

[0067] While the radial spacing between the tubes can be any distancedepending on the application, the radial spacing between tubes 30, 32,34 is approximately from about 1 inch to about 4 inches, preferably 1.9inches, and the axial lengths of tubes 30, 32, 34 can be any of avariety of different lengths that maintain outer tube 34 as the shortesttube, that maintain intermediate tube 32 as an intermediate length tube,and that maintain inner tube 30 as the longest tube. The tubes can bemade of any material that has sufficient strength to withstand theforces of the centrifuge, such as but not limited to, metal or plastic.

[0068] The length of innermost tube 30 is preferably adjustable. Theouter end can include a sleeve portion (not shown) that slides along thelength of the rest of the tube to allow length adjustment. The sleeveportion is fixed to the rest of the tube 30 by a set screw, or otherattachment mechanism. This allows for a fine adjustment of length of theinnermost tube 30 without having to replace the entire tube 30. This canbe helpful to match the tube to the plug size, as is discussed in moredetail below.

[0069] While all three of the tubes 30, 32, 34 are rigid tubes that havea circular cross section, it is preferred that outer tubular housing 34be made of a thicker or a stronger material than are tubes 30 and 32. Inaccordance with the invention, inner tube 30 is a relatively longer tubethat has a relatively small diameter, intermediate tube 32 is arelatively shorter tube that has a relatively larger diameter. The threetubes 30, 32, 34 are mounted such that their inner ends occupy a commonflat plane 62 (shown in FIG. 4 as a Y-Z plane), and the three tubes 30,32, 34 are concentric tubes that are centered on centrally located armaxis 64.

[0070] As perhaps best seen in FIGS. 4, 5 and 6, centrally locateddriven main body member 60 includes a dividing wall 66 that forms aninput mixture chamber 68 on one side thereof and a heavy material outputchamber 70 the other side thereof.

[0071] Each of the innermost and axially aligned tubes 30 contains aconveyer screw or auger 36 that aids in the removal of heavy material 24that builds up at end-cap ends 56 of arms 12, 14 during use ofcentrifuge 10 to separate light material 22 from heavy material 24, bothmaterials being contained within input mixture 16. The heavier material24 builds up to form a plug around the end of the innermost tube 30 andcovers a portion of the end cap 56. Conveyor screws 36 rotate about thecentral axis 64 of arms 12, 14 and aid in the movement of heaviermaterial 24 radially inward and through innermost tube 30 toward thecentrifuge's axis of rotation 72, whereas the heavier material 24 entersthe heavy output chamber 70 within driven member 60. This heavy material24 then moves out of centrifuge 10 by way of an exit cone 74 that isformed about rotational axis 72.

[0072] The apex of cone 74 lies on rotational axis 72, and its broadbase 76 terminates at an X-Z plane that is within a small-size annularhousing 78. The conveyor screws 36 can have different flighting 80designs on them to facilitate the removal of the heavier material. Asshown, the flighting 80 at the outer ends of the arms 12, 14 is smalland extends for a short distance, for example 6 inches, to assist inbreaking up the compacted heavier material 24 and help it begin movingtoward the exit cone 74. The middle length of the conveyor screw 36preferably has no fighting, as the heavier material 24 is pushed to somepoint there along by the head pressure created by the spinning of thecentrifuge 10. The inner end of the conveyor screws are flighted 80 tohelp pull the heavy material 24 towards the exit 82, and push it throughthe change of direction in the transition between the inner end of theinner tube 30 and the exit cone 74. The length of the flightingpreferably extends a distance that meets the heavy material once thehead pressure is no longer sufficient to advance the heavy materialthrough the inner tube 30.

[0073] In a preferred embodiment of the invention, and as shown in FIG.11, the inner ends of the conveyer screws 36 are cantilever-mounted toopposite sides of a centrally located hydraulic motor 84. However,within the spirit and scope of the invention, the outer ends of conveyerscrews 36 may be bearing-supported, as by the use of bearings (notshown) that are carried by outer tube-housing 34 or by end cap 56.

[0074] Input mixture 16 moves through the hollow center of shaft 28 andalong rotational axis 72 as arm assembly 12, 14 rotates about axis 72.Input mixture 16 then enters input chamber 68 within driven member 60.As best seen in FIG. 6, chamber 68 communicates with acylindrical-shaped volume 86 that is formed by the outer surface 88 ofinnermost tube 30 and the inner surface 90 of intermediate tube 32.Input mixture 16 now moves radially outward and throughcylindrical-shaped volume 86 to the distal end 92 of volume 86. At thelocation of end cap 56, input-mixture flow 16 separates into aheavy-material flow 24 and a light-material flow 22.

[0075] Heavy-material flow 24 first compacts at the end of the arms 12,14 and moves radially inward through innermost tube 30, this flow 24being assisted by conveyor screw 36, enters chamber 70, enters exit cone74, and then enters housing 78 wherein the heavy material 24 exitscentrifuge 10 at 82 as best shown in FIG. 1.

[0076] As perhaps best seen in FIG. 8, light-material flow 22concomitantly moves radially inward through a cylindrical volume 94 thatis formed by the outer cylindrical surface 96 of intermediate tube 32and the inner cylindrical surface 98 of outer tubular housing 34. At theradially inward end of volume 94, light-material flow 22 enterspassageways 100 that are formed in the metal walls of cone 74. By way ofpassageway 18, light-material flow 22 enters the intermediate sizeannular housing 102 whereat light-material flow 22 exits centrifuge 10at 104 as best shown in FIG. 1.

[0077] As input mixture 16 is forced to the distal ends of arms 12, 14by the rotation of the arm assembly about axis 72, the solid or heavymaterial 24 that is within input mixture 16 compacts or compresses toform a plug of heavy material 24 adjacent to and abutting the insidesurface of end cap 56. As a result, light-material flow 22 is forcedback toward the center of rotation 72 in the outer tube 32. As this plugof heavy material 24 builds up in size, heavy-material flow 24 is alsoforced back toward the center of rotation 72 in the inner tube 30.

[0078] More particularly, at the distal end of each of the two arms 12and 14, the end of long-tube 30 extends beyond the end of shorter-tube32. As solids are deposited at the distal end of arms 12 and 14 arelatively solid plug of heavy material 24 is formed, this plugincreases in thickness, along arm axis 64, until such time as the plugseals the end of long-tube 30. However, this plug thickness parameterdoes not increase enough to seal off the end of shorter tube 32. Thus,the plug partially defines the boundary of the two output flow paths 18and 20.

[0079] The thickness of the plug is regulated in part by the action ofconveyer screw 36. While not a limitation on the spirit and scope of theinvention, the elongated shaft of conveyor screw 36 does not havefighting or threading 80 along its entire length, but preferably hasflighting 80 only adjacent to its inner end, as best shown in FIG. 5,and described above.

[0080] Centrifugal forces on the heavy material 24 at the distal end ofarms 12, 14 combined with the hydrostatic head of the overlying liquidsand solids and assist in forcing the solids 24 through flow path 18, ina direction toward the center of rotation 72. The distance that solids24 move inward through tube 30 depends on the operating parameters ofcentrifuge 10 (for example the moment arm and the RPM), and on the typeof input mixture 16 that is provided to centrifuge 10. Usually, solidswithin input mixture 16 require the assistance of flighting 80 onconveyor screw arm 36 to move the solids along flow path 18. It ispossible, however, to have an input mixture 16 with a heavy materialcontent that does not require the presence of conveyor screws to assistthe heavy material through the inner tube towards the exit cone 74.

[0081] The thickness of the heavy-material plug that forms at the distalend of each arm 12, 14 is determined by an equilibrium condition that isestablished by the growth of the plug and the removal of the plug by wayof flow path 18 through the inner tube 30. Basically, the amount offlighting 80 adjacent to the inner end of conveyor screw 36 determinesthe equilibrium size of the plug. Assuming an input flow 16 havingrelatively constant amounts of heavy 24 and light materials 22, agreater amount of flighting 80 reduces the equilibrium plug size,whereas less flighting 80 increases the equilibrium size of the plug.This relationship is due to the effect that flighting 80 has on theremoval of the heavier material 24 by way of flow path 18.

[0082] The plug size is preferably at least at a minimum size or radialthickness to insure that the plug contacts only the ends of the innertubes 30 that define the input flow path 40, the light-material outputflow path 20, and the heavy material output flow path 18. This plug sizeshould be relatively conservatively designed to accommodate a temporaryreduction in the amount of heavy material 24 within input mixture 16(which reduction would cause the size of the plug to grow more slowly).If the heavier/lighter material composition of input mixture 16 is to bechanged for more than a temporary period, such as when a different typeof input mixture 16 is to be separated, the length of flighting 80 thatis provided on conveyer screw 36 may require modification to accommodatethis change. This modification is accomplished by removing an existingconveyer screw 36 and replacing it with a conveyer screw having adifferent fighting configuration 80. Other changes may also need to bemade, such as changing the RPM of the centrifuge or the length orspacing of the tubes 30, 32.

[0083] An important feature of the present invention is a mechanicalinterlocking construction and arrangement within the two arm assemblies12, 14 that enables the arm assemblies to be easily cleaned, to beeasily repaired by the selective replacement of components that make upthe arm assemblies, and to be easily modified, for example in order tochange the separation characteristics of centrifuge 10 to in order toaccommodate a change in input mixture 16.

[0084] With particular reference to FIGS. 5, 6 and 6A, when bolts 58 aretightened, end cap 56 and housing tube 34 operate to securely mounttubes 30 and 32 to centrally located main body member 60. While only thecircular outer end of the outer housing-tube 34 is physically engaged bya corresponding circular portion of end cap 56, as is shown at 106 ofFIG. 5, the radially inward force that is applied to housing-tube 34when bolts 58 are tightened securely mounts housing-tube 34 to drivenmember 60.

[0085] By virtue of a mechanical interlocking arrangement in accordancewith the invention, this radially inward force that is thus produced byhousing-tube 34 when bolts 58 are tightened also securely mountsintermediate tube 32 and inner tube 30 to driven member 60 in acantilever manner.

[0086] More specifically, and with particular reference to FIGS. 6 and6A, but without limitation to the specific details thereof, the end oftube housing 34 that is generally adjacent to rotation axis 72integrally carries a first annular ring 108 having an overhanging ringportion 110. The ring 108 is seated in and sealed with a circulardepression 112 in the main body member 60.

[0087] In addition, the corresponding end of intermediate tube 32integrally carries a second annular ring 114 having an overhangingring-portion 116, and having a ring portion 118 that underlies theoverhanging ring portion 110 that is carried by housing-tube 34. Thus,when housing-tube 34 is secured to main body member 60 by operation ofbolts 58, overhanging ring-portion 110 operates to physically trap theunderlying-ring portion 118 of intermediate tube 32, thus securingintermediate tube 32 to driven member 60.

[0088] In addition, the corresponding end of inner tube 30 integrallycarries a third annular metal ring 120 having an underlying ring-portion122. When intermediate tube 32 is secured to driven member 60 as abovedescribed, overhanging ring-portion 116 that is carried by intermediatetube 32 operates to physically trap the underlying-ring portion 122 ofinner tube 30, thus securing inner tube 30 to driven member 60.

[0089] In operation, should it become necessary to repair, serviceand/or modify arm assemblies 12, 14, all that need be done is to removebolts 58, disassemble the arm assemblies by removing the end caps 56 andtubes 30, 32, 34, perform the needed operations, and then reassemble thearm assemblies 12, 14.

[0090] When new and/or different tubes 30, 32, 34 are to be placedwithin centrifuge 10, the old tubes are removed and the new tubes areplaced within the arm assemblies 12, 14, the new tubes corresponding tothe old tubes in the manner in which they are mounted to driven member60 as above described.

[0091] With particular reference to FIGS. 3, 5 and 12, in accordancewith a feature of the invention the center of each of the two arm endcaps 56 includes a manually removable plug 124 that is press-fit withinend cap 56 and secured in place by operation of a manually removableC-ring 126. Manual removal of C-ring 126 and then plug 124, enables thecleaning/flushing of the distal end of arms 12 and 14, and may alsoprovide for the replacement of conveyer screws 36. Removal can beeffected by unscrewing the threaded collar 146 from the output shaft 148of the hydraulic motor 84. The end cap 56 also includes a first seal 128positioned between the end cap 56 and the annular end of the tubularhousing 34. A semi-conical liner 130 protects the inner wall of the endcap 56 from damage. The liner 130 can be made of metal, plastic oranother material that can withstand the intense pressure and conditionsin the centrifuge. A second seal 132 is positioned between the liner130, end cap 56 and annular end of the tubular housing 34. A plug collar134 having a circular cylindrical top end 136 and an outwardly slopingsemi-conical bottom end 138 is inserted into the end cap 56 from theinside so the bottom end 138 engages with the inner conical walls of theend cap 56. This engagement (see FIG. 5) keeps the plug 124 securelypositioned in the end cap 56 without risk of the plug 124 exitingthrough the aperture formed in the end of the end cap 56. The plugcollar 134 extends beyond the end of the end cap 56, and defines anannular groove around its inner diameter to receive the snap-ring collar126. A third seal 140 fits between the plug 140 and the plug collar 134.

[0092] With particular reference to FIG. 4, the dividing wall 66 thatdivides driven member 60 into input chamber 68 and heavy-material outputchamber 70 also operates to physically mount a hydraulic motor 84 at agenerally central location within output chamber 70 and generally on thecentrifuge's rotational axis 72. Hydraulic motor 84 contains a singlerotating member (not shown) that rotates on arm-axis 64, and that mountsthe inward ends of the two conveyor screws 36, as is best seen in FIG.11. An input hydraulic line 142 and a concentric output hydraulicline144 provide variable power to hydraulic motor 84, and thus variablespeeds of rotation for the two conveyor screws 36.

[0093] As shown in FIG. 11, the conveyor screw is mounted to a threadedcollar 146. The threaded collar is then mounted to the output shaft 148of the hydraulic motor 84. The threaded connection is preferably suchthat when the centrifuge 60 and auger screws 36 are in operation, thecollar is biased towards the hydraulic motor 84. An annular bearing 150is provided between the hydraulic motor and the threaded collar to keepcontaminants away from the output shaft 148 and ensure that the augerscrews keep spinning during operation.

[0094] Another important feature of the present invention is theconstruction and arrangement whereby the speed of rotation of armassembly 12, 14 can be varied independent of the speed of rotation ofthe conveyor screws 36 that are within each of the two arms 12, 14. Forexample, but without limitation thereto, this unique two-motorconstruction of centrifuge 10 enables the speed of motor 52 to be variedas a function the centrifugal force that is required to separate a giveninput mixture 16, whereas the speed of motor 84 can be independentlyvaried as a function of the amount of heavy material 24 that is within agiven volume of the given input mixture 16.

[0095] As perhaps best seen in FIG. 6, concentric hydraulic lines 142,144 are generally linear lines that extend generally coincident with thecentral axis of output cone 74 and the centrifuge's rotational axis 72.Hydraulic motor 84 rotates, while lines 142, 144 are stationary.Well-known rotary seals are provided to make a connection from lines142, 144 to motor 84.

[0096] There are several benefits gained by a centrifuge 10 constructedand arranged in accordance with the present invention. The concentrictubular rotating arms 12, 14 of the present invention provide anextremely long residence time during which an input mixture is subjectedto centrifugal separating forces. The longer this residence time, thelarger the amount of heavy material 24 that is removed from the inputmixture. In addition, heavy material 24 is deliquefied by means of thecompaction that occurs at the distal ends of the centrifuge's rotatingarm assemblies 12, 14. The centrifuge arm assemblies 12, 14 are easilydisassembled for maintenance, part replacement, and/or performancemodification. A centrifuge 10 in accordance with the present inventiongenerates tremendous centrifugal force in a machine having a relativelysmall physical size, and the centrifuge can be easily adjusted to handlea wide variety of input materials and flow rates. Since two separatedrive means 52, 84 are provided, the rate of arm rotation and the rateof removal of the heavy material 24 from the centrifuge 10 can beindependently varied, and removal of heavy material 24 from thecentrifuge10 is by way of a relatively large exit cone 74.

[0097] The centrifuge of the present invention can be utilized as anoxidation reactor with some structural modifications. The wet oxidationcentrifuge reactor disintegrates waste containing sludge in asupercritical oxidation reaction. A centrifuge is used to house thesupercritical oxidation reaction to create a more efficient environmentfor generating supercritical conditions (i.e., high pressure, hightemperature). The influent is typically in the form of a sludge slurryinjection. After undergoing the oxidation reaction, the resultingeffluent is comprised of ash, CO2, and H2O, and other by-productsdepending on the constituents of the incoming slurry. FIG. 13 provides aschematic overview of the various process zones and related reactorparameters for an embodiment of the supercritical wet oxidationcentrifuge reactor. FIG. 14 is an enlarged view of the centrifuge arm inFIG. 13 and includes additional details regarding the geometry andconfiguration of the arm internal portions.

[0098] Several identifiable zones exist within the centrifuge reactor200 during processing. Referring to FIGS. 13-14, generally the influentfirst enters an entry zone, next a sludge thickening zone 202, then anoxidation reaction zone 204, next a cooling zone 206, and finally anexit zone. Tables 1-2 herein and FIGS. 15 through 18 both list andillustrate examples of the supercritical wet oxidation centrifugereactor parameters. The key reactor parameters are pressure, specificvolume, velocity, and temperature, which all provide insight into thereaction process occurring within the various reactor zones. Thefollowing provides a general overview of the centrifuge structure andspecific details with respect to the centrifuge reactor parameters.

[0099] Referring to FIGS. 22 and 23 as representative of a preferredembodiment for this discussion, the oxidation centrifuge 660 generallyincludes a main body portion 602 and at least two centrifuge arms 604extending from the main body portion 602. The main body portion 602 issuspended from a framing portion 646 and includes a bottom portion 652that extends into a discharge chamber 654 or tank. The discharge chamber654 serves as the base portion of the centrifuge reactor 200. Inoperation, the main body portion 602 and arm portions 604 rotate about avertical axis 640 through the center of the main body portion 602. Bothan influent manifold 644 and an effluent manifold 638 are formed in thetop 648 and bottom center portions, respectively, of the main bodyportion 602. The centrifuge arms 604 are in communication with theinfluent 644 and effluent 638 manifolds.

[0100] The centrifuge arms include a beginning portion 210 and an endportion 212. The centrifuge arm beginning portion 210 includes threeconcentric tubes that define three concentric channels. The outerchannel 214 (or outer annular region) is in communication with theeffluent manifold 638, the middle channel 216 (or intermediate annularregion) is in communication with the influent manifold 644, and thecenter channel 218 (inner tube) is in communication with the effluentmanifold 638. In an alternate embodiment, the outer channel 214 may bein communication with a centrate outflow channel (not shown) or port orno outer channel 214 may be present. The outer channel 214 generally hasa consistent cross-sectional area. The middle channel 216cross-sectional area increases from the end 220 nearest the main body602 portion to the center portion of the middle channel 216 and thendecreases from the center portion to the end 222 nearest the end portionof the centrifuge arm. The center channel cross-sectional area decreasesfrom the end 224 nearest the main body portion to the end 226 nearestthe end portion of the centrifuge arm 604.

[0101] Central to the center channel is a cooling tube or probe 228. Theprobe 228 introduces cooling water 230 to the center channel. The probe228 is connected to a cooling water supply pipe 230 that extends fromthe side of the discharge chamber and up the center of the effluentmanifold 638. The probe(s) 228 extend outwardly from the center of theeffluent manifold 638 into the center of the center channel 218. Theprobes 228 can be mutually or independently adjustable and can also beconfigured to automatically adjust depending on the pressure in thecenter channel 218.

[0102] The end portion 212 of the centrifuge arm 604 includes twoconcentric tubes that define two concentric chambers: an outer chamber232 and an inner chamber 234. The outer chamber 232 is in communicationwith the middle channel 216. The inner chamber 234 is in communicationwith the center channel 218. The outer chamber 232 is also incommunication with the inner chamber 234. The outer chamber 232cross-sectional area increases from the end 236 nearest the main bodyportion 602 to the opposite end 238. The inner chamber 234cross-sectional area decreases from the end 240 nearest the main bodyportion 602 to the opposite end 242. The probe 228 extends from themiddle channel 216 into the inner chamber 234 and acts a plunger topartially block and control the flow of effluent from the inner chamber234 to the middle channel 216.

[0103] A flow path is defined through the main body portion 602 andcentrifuge arm 604 during operation of the centrifuge reactor 200. Theinfluent sludge slurry injection enters the influent manifold 644 at thetop of the centrifuge main body 602 and flows down to openings definedby the centrifuge arm middle channels 216. The forces exerted by therotation of the centrifuge 200 causes the slurry to enter the middlechannels 216. The influent slurry flows along the middle channel 216 tothe beginning of the outer chamber 232 on the end portion 212 of thecentrifuge arm 604. The area from the beginning of the influent manifold644 to the beginning of the outer chamber 232 on the end portion 212 ofthe centrifuge arm is known as the entry zone 201.

[0104] Centrate 246 flows out of the middle channel 216, into the outerchannel 214, and back into the effluent manifold 638 in the center ofthe main body portion 602 (centrate is the resulting separated liquidfrom a centrifuge process). In alternate embodiments, the centrate 246may exit the centrifuge 200 via a centrate port (not shown) or no outerchannel may be present. In the middle channel 216, the influent beginsto thicken. This area is known as the sludge thickening zone 202.

[0105] The influent continues into the outer chamber 232 and to the end212 of the centrifuge arm. The end portion 212 of the centrifuge arm 604is heated by a heating element 244. The influent/effluent next flowsinto the inner chamber. The influent sludge is disintegrated inoxidation reactions in the outer 232 and inner 234 chambers. This regionis known as the oxidation reaction zone 204.

[0106] The oxidized influent (now effluent) mixes with cooling water 230from the probe 228 and flows into the center channel 218 of what iscalled the cooling zone 206. The effluent finally flows into theeffluent manifold 638 in the center of the main body portion 602. Theeffluent manifold 638 and surrounding regions are known as the exit zone208. In some embodiments, the effluent in the effluent manifold 638mixes with any centrate 246 present and flows down into the dischargechamber 654 at the base of the centrifuge 200. In other embodiments, thecentrate 246 may be separately removed from the centrifuge 200 or nocentrate 246 is present.

[0107]FIGS. 3 through 6 trace the pressure, specific volume, velocity,and temperature versus the centrifuge arm distance (see Table 1 forcorresponding data). The graphs illustrate the values of these fourparameters taken along the centrifuge arm as the waste sludge makes itsway from the influent manifold 644 central to the main body 602 to theend 212 of the centrifuge arm 604 distal to the influent manifold 644and back to the beginning 210 of the centrifuge arm proximate theeffluent manifold 638, where the reactants exit the centrifuge 200.TABLE 1 spec arm temp vol pressure velocity time (ft) (deg F.) (cuft/lb) (psi) (fps) (sec) THICKENING 0.45 180 0.0165 0 0.17 0 ZONE 0.65180 0.0165 107 0.17 1.20 0.85 180 0.0165 254 0.17 2.40 1.05 180 0.0165439 0.17 3.60 1.25 180 0.0165 663 0.17 4.80 1.45 180 0.0165 927 0.176.00 1.65 180 0.0165 1229 0.17 7.20 1.85 180 0.0165 1571 0.17 8.41 2.05180 0.0165 1951 0.17 9.61 2.25 180 0.0165 2371 0.17 10.81 OXIDATION 2.45180 0.0165 2829 0.05 12.67 ZONE 2.66 734 0.0360 3155 0.11 15.36 2.87 8690.1800 3241 0.53 16.01 3.08 947 0.1900 3295 0.56 16.39 3.28 1020 0.21003348 0.62 16.75 3.53 1108 0.2300 3411 0.55 17.17 3.71 1170 0.2500 34530.60 17.48 3.88 1229 0.2600 3495 0.63 17.76 4.06 1285 0.2750 3537 0.6618.03 3.88 1290 0.2800 3497 14.27 18.06 3.71 1292 0.2850 3459 14.5218.07 3.53 1295 0.2850 3423 14.52 18.08 3.28 1300 0.2900 3375 3.69 18.113.28 1300 0.2900 3375 3.69 18.11 COOLING/ 2.98 216 0.0178 3275 20.0018.13 EXIT ZONE 2.67 216 0.0181 2476 10.07 18.15 2.37 216 0.0186 177710.31 18.18 2.18 216 0.0192 1391 3.64 18.21 1.98 216 0.0201 1047 2.2718.28 1.79 216 0.0214 748 1.72 18.37 1.60 216 0.0236 498 1.45 18.49 1.41216 0.0270 300 1.37 18.63 1.22 216 0.0325 159 1.49 18.76 1.03 216 0.041172 1.93 18.87 0.83 216 0.0536 28 2.87 18.95 0.64 216 0.0702 7 4.49 19.010.45 216 0.0887 0 5.82 19.04

[0108] The centrifuge arm 604 length is an important factor as itrelates to the pressure within the centrifuge arm 604. The centrifugalforces generated by the centrifuge 200 are related to the distancemeasured from the center axis 248 of the centrifuge 200 to theparticular point within the centrifuge arm (“R” in FIGS. 13-14). Thegreater the value of R, the greater the pressure in the arm 604. Asshown in Table 1 and FIG. 15, the pressure increases from the center ofthe centrifuge 200 to the end of the centrifuge arm 604 (as the materialflows in and through the reaction zone) and then decreases materialflows from the end of the centrifuge arm 604 to the center of thecentrifuge 200 (as the reaction by-products flow through the centerchannel 218 or inner tube).

[0109] In greater detail, as the sludge slurry is injected into the mainbody 602 and travels down the influent manifold 644 and into thebeginning portion 210 of the centrifuge arms 604, the slurry is notunder any appreciable pressure (see Table 1). Both the velocity andtemperature of the sludge slurry remain constant in the beginningportion 210 of the centrifuge arm 604. In addition, because the densityof the influent remains constant in the beginning portion 210 of the arm604, the specific volume also remains constant (specific volume is theinverse of density). As the sludge slurry moves from the influentmanifold 644 to the middle channel 216 of the centrifuge arm 604, thecross-sectional area of the middle channel 216 begins to decrease as theoverall diameter of the middle channel 216 decreases. As the middlechannel 216 narrows in diameter, the sludge slurry begins to thicken.This area of the centrifuge arm is known as the sludge thickening zone202.

[0110] In one embodiment, as the sludge thickens, centrate 246 orlighter fluids flow away from the sludge through exit ports in themiddle channel 216 into the outer channel 214 and back toward the centerof the main body portion 602. The centrate 246 ultimately flows into theeffluent manifold 638 and into the discharge chamber 654 in the base ofthe centrifuge reactor 200. The presence of an outer channel 214 allowsthe lighter fluid 246, if any, to exit the centrifuge 200 without beingpart of the oxidation reaction. This lighter fluid 246 is decanted fromthe sludge by the centrifuge 200 in its normal operation prior toreaching the reaction zone 204. In some circumstances, the influent maynot have a high fluid content. In those instances the exit ports andouter channels 214 may not be necessary.

[0111] As illustrated in the graph in FIG. 15 and by the values incolumn 4 of Table 1, as the influent waste sludge enters the sludgethickening zone 202, the pressure steadily increases. Because thepressure for non-gaseous phase materials is generally P=F/A, whereF=force in pounds and A=area in square inches, the decreasing diameterof the middle channel 216 sludge thickening zone 202 causes thecross-sectional area of the middle channel 216 to decrease and thus thepressure to increase. In addition, because the sludge thickening zone202 forms a partial solids plug in the middle channel 216, the velocityin the sludge thickening zone remains low and constant (see FIG. 17 andcolumn 5 of Table 1). Because the sludge thickening zone 202 is in anarea of the centrifuge arm 604 that is not heated, the temperature inthe sludge thickening zone remains relatively constant (see FIG. 18 andcolumn 2 of Table 1). The partial plug of sludge helps maintain arelatively constant influent density (and corresponding constantspecific volume as illustrated by the graph in FIG. 16 and by the valuesin column 3 of Table 1) within the sludge thickening zone 202. As thethickened and dewatered sludge exits the sludge thickening zone 202, itis injected with an oxidant, such as oxygen. The dewatered, thickened,and oxidant injected sludge next enters the end portion 212 of thecentrifuge arm 604.

[0112] The end portion 212 of the centrifuge arm 604 is typically heatedusing an external heating coil 244. In other embodiments, an electrodeinternal to the end portion of the centrifuge arm 604 may also be used.The end portion 212 of the centrifuge arm 604 is also known as theoxidation reaction zone 204. The oxidation reaction occurs in this area.The oxidation reaction disintegrates the sludge and creates an effluentmixture of ash, CO₂, and H₂O. Other by-products may also be presentdepending on the constituents in the influent material. A combination ofhigh temperatures created by the heating coil 244 and high pressurescreated by both and the centrifuge 200 and the centrifuge arm 604geometry act together to create an environment with supercriticalconditions. The oxidant enriched sludge undergoes an oxidation reactionin the supercritical environment.

[0113] The oxidation reaction zone 204 portion of the centrifuge reactor200 includes outer 232 and inner 234 chambers. The cross-sectional areaof the outer chamber 232 increases and the cross-sectional area of theinner chamber 234 decreases as the influent sludge flows toward the end212 of the centrifuge arm 604. In the oxidation reaction zone 204, theinfluent is primarily comprised of materials in the solid and gasphases. As a result, the influent in the oxidation reaction zone 204responds at least partially according to the ideal gas law (Pv=nRT,where P=pressure, n & R are constants, and T=temperature). If the idealgas law applies, the pressure and specific volume are directlyproportional to the temperature. Regardless of whether the ideal gas lawapplies, the centrifugal forces generated by the centrifuge 200 causethe pressure to rise steadily as the distance (“R”) from the center 248of the centrifuge 200 increases.

[0114] The resulting pressures from the centrifuge 200 and from theincreasing temperature in the oxidation reaction zone 204 cause thepressure to increase from the beginning of the outer chamber 232 to theend of the outer chamber 232 in the middle portion of the oxidationreaction zone 204 at the end of the centrifuge arm 604 (see FIG. 15 andcolumn 4 of Table 1). The pressure increases as the sludge flows towardthe end 212 of the centrifuge arm 604 and toward the inlet 250 for theinner chamber 234. The inlet 250 for the inner chamber 234 has an areathat is significantly smaller than the area of the outer chamber 232 atthe end 212 of the centrifuge arm 604. In addition, this point is at thefarthest distance from the center axis 248 of the centrifuge 200. As aresult, the centrifugal forces and the geometry cause the pressure toincrease to a maximum in an area adjacent to the inlet 250 of the innerchamber 234.

[0115] The pressure decreases after the sludge flows reverses directionand flows beyond this pinch point 250 and into the inner chamber 234.Although the temperature continues to rise, because substantially all ofthe influent sludge has been disintegrated in an oxidation reaction inthe outer chamber 232, the geometry of the inner chamber 234 begins tohave an effect on the pressure of the effluent oxidized sludge mixture.In addition, the centrifugal forces on the effluent sludge decrease asthe value of R decreases and the effluent moves closer to the axis ofrotation 248. The side section of the inner chamber is generallyfunnel-shaped 252 and the diameter of the inner chamber 234 includes aconstant portion 254 from the end of the centrifuge arm 604 to a portionnear the middle of the end portion 212 of the centrifuge arm 604, and aportion 252 with an increasing diameter from the middle 256 of the endportion 212 of the centrifuge arm 604 to the beginning of the centrifugearm 604 adjacent the main body 602. This increasing diameter helps causea reduction in pressure (pressure=F/A, F=force in pounds, A=area insquare inches, increase in diameter increases cross-sectional area, thusdecreasing pressure).

[0116] The specific volume of both the thickened sludge and oxidizedsludge steadily increases throughout the oxidation reaction zone 204(see FIG. 16 and column 3 of Table 1). As the solids are disintegrated,the density decreases throughout the oxidation reaction zone 204. Inaddition, because the ideal gas law is assumed to apply in at least theouter chamber 232 of the oxidation reaction zone 204, the fact that thetemperature increases causes the volume to increase thereby causing thedensity to decrease (density=mass/volume). Because density is theinverse of specific volume, the specific volume increases.

[0117] The velocity of the sludge increases slightly as it moves towardthe inlet 250 of the inner chamber 234 (see FIG. 17 and column 5 ofTable 1). This increase is a result of the increasing pressure. As thewaste moves through the inlet of the inner chamber 234, the velocity ofthe waste increases dramatically. This increase is due to the effect ofmoving through the much smaller inlet 250 of the inner chamber 234 (seeregion “A” of FIG. 17). As the diameter remains constant for the middlethird of the inner chamber 234, the velocity also remains constant (seeregion “B” of FIG. 17). As the diameter of the inner chamber 234increases, the velocity of the oxidized waste steadily decreases (seeregion “C” of FIG. 17). Correspondingly, the pressure also decreasessteadily as the waste moves from the inlet 250 of the inner chamber 234toward the larger diameter end 256 of the inner chamber 234. Thetemperature within the oxidation reaction zone 204 steadily increases asthe waste product moves from the beginning 236 of the centrifuge arm tothe end 238 of the centrifuge arm through the outer chamber 232 and backto the beginning 240 of the centrifuge arm 604 through the inner chamber234. The increase in temperature of the waste sludge as it moves throughthe oxidation reaction zone 204 is primarily a result of the residencetime of the waste sludge in the heated zone 204. The longer the wastesludge is heated, the higher the temperature of the waste sludge.

[0118] As the oxidized wastes travel further along the inner chamber 234toward the effluent manifold 638 in the main body 602, the oxidizedwastes (effluent) flows around the cooling tube or probe 228 thatextends into the inner chamber 234 from the cooling zone 206 centerchannel 218. The probe 228 introduces cooling water 230 to the ash andCO₂ mixture exiting the oxidation reaction zone 204. As a result, thevelocity again increases due to the diminished cross-sectional areawithin the inner chamber 234 (see region “D” in FIG. 17). The resultanteffluent of ash, CO₂, and H₂O exits the inner chamber 234 of the heatedoxidation reaction zone 204 and enters the center channel 218 of thecooling zone 206.

[0119] The diameter of the center channel 218 in the cooling zone 206increases from the beginning of the cooling zone to the end of thecooling zone adjacent the effluent manifold. The geometry of the coolingzone 206 center channel 218 (increasing diameter) causes the pressure inthe cooling zone to steadily decrease. The pressure decreases as theeffluent moves from the constricted inlet 258 of the center channel 218to the larger diameter portion of the center channel 218.

[0120] As mentioned above, the length of each probe 228 may be adaptedto manually or automatically adjust depending on the pressure in eachcentrifuge arm 604 cooling zone 206. The head 229 of the probe 228serves as a throttle block 229 to help maintain pressure levels in thereaction zone 204 and to generally help control the entire process. Ifthe probe 228 were substantially removed from the oxidation reactionzone 204 inner chamber 234, the oxidation reactions would discontinue.By substantially removing the probe 228 from the oxidation reaction zone204, the CO₂ gases within the reaction zone 204 are allowed to expandinto the cooling zone 206 thereby increasing the volume and decreasingthe density. The drop in density correspondingly causes the pressurewithin the reaction zone 204 to decrease thereby causing the oxidationreaction to discontinue. If the probe 228 is inserted too far into theoxidation reaction zone 204, the cooling water 230 can cause theoxidation reaction to discontinue by quenching the reaction. The coolingwater 230 can cause the temperature within the reaction zone 204 to droplow enough to cause the oxidation reactions to cease. The probe 228 canalso be adjusted to manipulate the amount of centrate 246 that flows outof the outer channels 214. The further the probe 228 is inserted intothe reaction zone 204 (without quenching the reactions), the greater thepressure is within the reaction zone 204. As a result, the pressure inthe sludge thickening zone 202 is also increased and the amount ofcentrate 246 that escapes via the outer channel 214 is increased. If theprobe 228 is only inserted far enough into the reaction zone 204 tomaintain the oxidation reactions, the pressure levels in the reactionzone 204 will be toward the lower end of acceptable pressure levels tomaintain oxidation reactions. As a result, the pressure levels in thesludge thickening zone 202 will also be reduced thereby allowingpotentially all of the fluids to pass into the reaction zone 204. Insuch a case, the centrate 246 flow rate may be greatly reduced or evenstopped.

[0121] As illustrated best in FIG. 16, the specific volume drops as itenters the cooling zone 206 (in comparison to the reaction zone 204) andthen steadily increases throughout the cooling zone 206. The initialdrop is the result of a higher density because the CO₂ gases are tightlyconstricted around the probe 228. As mentioned above, the densityinversely influences the specific volume. The higher density of thegases creates a lower specific volume. Because the pressure andtemperature both decrease in the cooling zone 206, the CO₂ gases createdfrom the oxidation reaction begin to expand in the cooling zone 204. Asa result, the volume of the effluent expands and the density decreases(density=mass/volume). The specific volume, which is the inverse ofdensity, therefore increases in the cooling zone 206.

[0122] The velocity of the effluent increases throughout the coolingzone 206. In the beginning of the cooling zone 206, the center channel218 cross-sectional area is reduced greatly by the presence of the probe228 within the channel 218. As a result, the velocity greatly increasesthrough that region (see region “D”). The velocity drops 206 throughmost of the cooling zone as the cross-sectional area increases(velocity=area/area). At the end of the cooling zone, the expanding CO₂gases cause the velocity to increase as the effluent enters the effluentmanifold (see “F” in FIG. 17).

[0123] Because of the injection of cooling water 230, the temperaturewithin the cooling zone 206 is significantly less than the temperaturein the oxidation reaction zone 204. Also because of the injection ofcooling water 230, the temperature within the cooling zone 206 remainssubstantially constant.

[0124] After exiting the cooling zone 206, the cooled effluent mixeswith any centrate from the sludge thickening zone and flows into theeffluent manifold 638 in the main body 602 portion and down into thedischarge chamber 654 at the base of the centrifuge reactor 200. Theeffluent mixes with cooling water in the discharge chamber 654 tofurther lower its temperature. As an additional step, the effluentsolids may be sent to a filtering process to separate the effluentsolids from the effluent fluids. TABLE 2 Supercritical Wet OxidationCentrifuge Reactor Parameters Parameter Value Units speed 2609 rpmsludge throughput 50 gpm 417.0 lb/min influent sludge % solids 2.0% 8.3lb/min influent sludge temperature 180 deg F. influent sludge specificvolume .0165 cu ft/lb thickened sludge % solids 16.0% thickened sludgethroughput 6.2 gpm 52.1 lb/min thickened sludge water content 43.8lb/min SHts (specific heat of 1.00 btu/lb/deg F. thickened sludge)Sludge % volatile solids 70.0% 5.8 lb/min HVvs (heating value of 10000btu/lb/deg F. volatile solids) O₂ dosage requirement 1.80 lb/lb VS O₂injected 10.5 lb/min CO₂ production rate 2.48 lb/lb VS CO₂ produced 14.4lb/min cooling wet rate 95 gpm cooling water temperature 125 deg F.CO₂ + H₂O produced in combustion zone 54.3 lb/min in cooling zone 846.6lb/min Products % CO₂ 1.7% cooling water spec. vol @ 0.0167 cu ft/lb

[0125] Table 2 includes parameters for one embodiment of the reactor(also see corresponding FIGS. 13-14). In other embodiments, it isforeseen that the reactor parameters will vary depending on manyvariables. Examples of such variables include but are not limited to theinfluent sludge characteristics (i.e., constituents in the sludge),power limitations, and logistical considerations such as the size of thereactor.

[0126] In addition to parameters related to the area and the influentcharacteristics delineated in Table 2, Table 3 includes parametersrelated to the geometry of the centrifuge arm internal channels andchambers. The location of the various zones in the centrifuge arms withrespect to the axis of rotation of the centrifuge is important inrelation to the centrifugal forces generated by the centrifuge. Table 3and FIG. 14 describe and illustrate the various geometrical parameters.TABLE 3 Supercritical Wet Oxidation Centrifuge Reactor Parameters Param-eter Description Value Units R1 radius from the centrifuge center axisof 29.40 inches rotation to the beginning of the heated reaction zoneportion of the centrifuge arm R2 radius from the centrifuge center axisof 48.70 inches rotation to the end of the centrifuge arm R3 radius fromthe centrifuge center axis of 39.40 inches rotation to the middle of theprobe head R4 radius from the centrifuge center axis of 5.40 inchesrotation to the oxidation reaction effluent ports into the effluentmanifold D1 diameter of centrifuge arm at the 6.00 inches end of arm r₁radius from the centrifuge center axis 0.45 feet of rotation to thecentrate exit ports IDmt inside diameter of oxidation 8.49 inchesreaction effluent ports ODit_(min) outside diameter of inner chamberinlet 1.70 inches ODit_(chk) outside diameter of end of inner chamber3.00 inches funnel-like portion IDit_(min) inside diameter of innerchamber inlet 1.25 inches IDit_(chk) inside diameter of end of innerchamber 2.50 inches funnel-like portion IDit_(max) maximum insidediameter of center 7.00 inches channel (inner tube) ODct outsidediameter of probe or cooling tube 2.00 inches X1 length of sludgethickening zone 1.00 inches X2 length of funnel-like portion of 3.00inches inner chamber X3 length from sludge thickening zone to 11.00inches wide end of funnel-like portion of inner chamber Vchk velocity ofeffluent adjacent probe 20.0 feet/second throttle block Amax maximumcross-sectional area of 26.00 inches² reaction zone Amin minimumcross-sectional area of 21.21 inches² reaction zone Ait_(min) minimumcross-sectional area of inlet 1.23 inches² of inner chamber Ait_(chk)maximum cross-sectional area of inner 4.91 inches² chamber adjacent wideend of funnel-like portion Ait_(max) maximum cross-sectional area ofinlet 38.48 inches² of inner chamber

[0127] Referring first to FIG. 19, the basic centrifuge structure asdescribed above is slightly modified to structurally convert thecentrifuge from traditional applications to a structure suitable for useas an oxidation reactor. Hereinafter, mention is made of the centrifugeas being used in a supercritical oxidation reaction process. It iscontemplated that the centrifuge can also be used in a subcriticaloxidation reaction process as well as in basic chemical reactionprocesses. For convenience, the term “oxidation reaction process” isused as a nonlimiting descriptive term.

[0128] Referring first to FIG. 19, a section view of a centrifuge 300modified for use as an oxidation reactor is shown. The basic structureof this centrifuge is identical to that described above, with similarparts given similar descriptive labels. However, similar parts are givendifferent numbers in the descriptions of the various embodiments herein.For example, in one embodiment the main body of the centrifuge may benumbered 316 while in another embodiment, the main body is 402. Theprimary distinction between FIG. 19 and an earlier described embodimentof this invention is that the structure has been modified to include aheat source 326 at the terminal end 302 of each of the arms 304, 306. Inthis instance, an electrode 308 is provided attached to the inner side310 of the end cap 312. Any type of heat source 326 can be used which issufficient to raise the internal temperature in the reaction zonedefined at the end of each of the arms 304, 306 to the criticaltemperatures. Such heat sources 326 include, but is not limited to, glowplugs, electric resistive heaters, and radiative heaters. An additionalchange is that the augers used to remove the heavy material from thecentrifuge structure as described above have been themselves removed toallow exit of the reacted by-products, or reactants, through the outletaperture 314, as described below.

[0129] The structure of FIG. 19 includes a main body 316 with at leasttwo diametrically opposed arms 304, 306 extending therefrom. An inletpipe 318 connects to one end 320 of the main body 316, and an outletaperture 314 is formed on the opposite end 322 of the main body 316. Theinlet pipe 318 carries material to the main body 316, and also forms theaxis 324 about which the centrifuge 300 rotates. Typically, thecentrifuge 300 spins on a vertical plane (into and out of the page inFIG. 19) but can be oriented in any manner desired. Various channels areformed inside the main body 316 and arms 304, 306 of the centrifuge 300,as described above and below herein.

[0130] An inflow channel 328 is formed by the inlet pipe 318 and extendsfrom the inlet pipe 318 into both of the arms 304, 306. The inflowchannels 328 in both arms are identical, so only the flow channels 328in one arm are described herein. Inside the arm 304 there is a centraltube 330 that acts as an exit path and is in communication with theoutlet aperture of the main body 316. Spaced concentrically outwardlyfrom the central tube 330 and attached to the main body 316 is anintermediate tube 332, which forms an annular space around the centraltube 330. This inner annular space 334 is part of the inflow channel 328incoming flow path for the incoming sludge material. The arm housing 336forms an annular space 338 around the intermediate tube 332. This outerannular space 338 forms part of the exit path for the decanted liquidsas described above. The outer annular space 338 is in communication withthe high fluid (decanted liquid) exit channel 340 formed in the mainbody as described above. The central tube 330 can be somewhat longerthan the intermediate tube 332 for reasons described above.

[0131] The end 342 of the arm 304 forms a cavity 344, which is thereaction zone for the oxidation reactor. The curved cavity 344 isdefined by an end cap 312, which is held in place by a series ofelongated bolts 346, which extend from the end cap 312 to the main body316. Each tube has its own base frame 348 which fits into the main body316 and interlocks with the base ring 350 of the adjacent tube, andunder the compressive force of the attachment bolts 346, each of thebase rings 350 form a tight seal with the main body 316, as describedabove. The interlocked base rings 350 allow the sectional formation andremoval of the arm 304 and its inner parts. The end cap 312 seats on theouter end 342 of the arm housing 336 and under the compression of theelongated bolts 346, compressing the arm housing 336 towards the mainbody 316. The base ring 350 of the arm housing 336 interlocks with thebase ring 350 of the intermediate tube 332, which in turns interlockswith the base ring 350 of the inner tube 330, and thus holds all of thetubes in sealed engagement with the main body 316.

[0132] A set of bearings 352, only one of which is shown, supports theinlet pipe 318, and thus also the cantilevered centrifuge 300. As thecentrifuge 300 spins, preferably with the arms 304, 306 moving in avertical plane, great pressures are formed at the ends 342 and each arm304, 305 in the reaction zone area. The pressure is determined primarilyby the revolutions per minute (spin speed) and the length of the arm304, and is easily controlled. As noted above, a motor (not shown) isused to spin the centrifuge 300, preferably by turning the inlet pipe318.

[0133] A heating element 326, such as an electrode 308, is positioned inthe reaction zone to provide the heat required for the supercriticaloxidation reaction process. The temperature required for the oxidationreaction to occur is described above in detail, and is generally above700° F. and 3200 psi.

[0134] Oxygen is required, along with heat and pressure, to cause theoxidation reaction to occur. Oxygen can be fed directly into thereaction zone by a separate piping system (not shown in this embodiment)or can be permeated in the incoming sludge material as it enters thecentrifuge 300. In either manner, oxygen is brought into the reactionzone in addition to the heat and pressure in the reaction zone, helpingfacilitate the oxidation reaction taking place.

[0135] Generally, when the sludge plug forms in the reaction zone, andthe sludge is subjected to extreme pressures, heat, energy and oxygen,the oxidation reaction process occurs. The by-products of the reactionoxidation process are typically mainly ash, CO2 or H2O. The reactionby-products can also include other elements which are not entirelytransformed during the reaction process to ash, CO2 or H2O, dependingupon the constituents of the incoming sludge. The reaction by-productsexit the centrifuge through the inner tube 330, as is described in moredetail below. Because the reaction zone is at very high pressure and theexit aperture 314 is at ambient pressure, the reaction products willsomewhat automatically flow through the inner tube 330 toward the outletaperture 314 due to the pressure drop. As the reaction products flowthrough the inner tube 330, at some intermediate position 356 of theinner tube 330, there is a flash steam zone where the pressure hasdecreased sufficiently to allow the H2O reaction by products totransition to a steam state. This further helps expel the reaction byproducts out the outlet aperture 314, which is a atmospheric pressure.

[0136] In more detail, in the instant invention, with respect to FIG.19, the incoming sludge preferably includes a sufficient oxidant levelto withstand being compacted as it moves from the inlet 318 to the endof the arm 342, as described above. The decanted liquid is extracted todewater the sludge prior to the oxidation reaction. The sludgeconcentrates as it moves to the reaction zone at the distal end 342 ofthe arm 304. With the addition of heat and with the oxidant in thecompacted material, the oxidation reaction process occurs in a reactionzone. The oxidation reaction is started by the heat energy incombination with the oxidant and the fuel content of the material. Onceit begins, the oxidation reaction is preferably self-sustaining and theheat source can be turned off. It can be turned on as needed to maintainthe desired temperature. The resulting reaction by-products are flushedfrom the centrifuge 300 through the inner tube 330 and out the outletaperture 314. The removal of the decanted liquid is identical to thatdescribed above.

[0137] Generally, a temperature of approximately 800 to 1200 degreesFahrenheit is required for the oxidation process to occur. The pressuregenerated at the end 342 of the centrifuge arm 304 in the reaction zoneshould be approximately 3,000 to 3,500 psi, and the required oxidantlevel depends on the volatility of the material in the mixture beingoxidated in the reaction. While the oxidant can be included in theincoming material, it is more efficient if it is added to the heaviermaterial as it is compacted. The compaction (drying out) process removessome of the oxidant from the material. If the oxidant is added after themajority of the compaction has occurred, then only the necessary levelof oxidant is required to be added to the material. These values arerepresentative only, as are the values described elsewhere herein.

[0138] In using the centrifuge 300 of the present invention as anoxidation reactor, the pressure can be easily controlled by the lengthof the arm 304 extending from the main body 316 and the spin speed ofthe centrifuge 300 itself. This is a significant advantage over theexisting supercritical oxidation reactor processes which require complexpressure generation, release and control equipment. Further advantagesare described hereinafter. The reaction products from this process canbe taken directly from the outlet aperture 314 and disposed of asdesired, such as being encased in concrete or handled by any other knowntype of disposal techniques.

[0139] It is contemplated that the centrifuge 300 of the presentinvention can be connected in series with at least a second centrifuge,if desired. For instance, a first centrifuge can be used to de-water thesludge to a sufficient level for the oxidation reaction process, withthe outlet of the first centrifuge being connected to the inlet of thesecond centrifuge. If the second centrifuge is modified to act as anoxidation reactor, then the outlet of the first centrifuge can flow intothe inlet of the second centrifuge where the oxidation reaction processtakes place. Several centrifuges can also be hooked together if desired.

[0140] During the oxidation reaction process, whether critical,subcritical, supercritical, or any other reaction process performed inthe centrifuge 300 of the present invention, the process parameters canbe monitored and controlled by the placement of appropriate sensors inthe centrifuge 300, combined with automatic feedback of the sensor datato either a human-controlled center, or to an automated center includinga computer, microprocessor, and the desired programming software tointerpret and respond to the feedback from the sensors. The sensors canbe placed in several places in the centrifuge 300 for monitoring thecritical process characteristics, such as along the inside 358 oroutside 360 of the arm 304, in the reaction zone, in the exit tube 330and outlet aperture 314 areas, and in the inlet path 328 as well as theinlet pipe 318. The sensors allow the measurement of the physicalcharacteristics such as, but not limited to, the heat level, the oxidantcontent and the pressure. The control system, whether human orautomated, can react to the sensor data to decrease, increase ormaintain the various input data, such as spin speed, temperature,oxidant content and possibly even sludge chemical makeup to helpoptimize the oxidation reaction.

[0141] The centrifuge 300 of the present invention used as an oxidationreactor is not limited to two diametrically opposed arms 304, 306. It iscontemplated that any number of arms can be implemented as long as theproper balance is created to allow the spin speeds required to generatethe desired pressure.

[0142] It is also contemplated that the outlet flow path 334 for thedecanted liquid can be blocked to make all of the input sludge materialin the inlet pipe 318 go through the reaction zone in a case requiringthe entire content of the sludge to be reacted. The decanted liquidoutlet apertures (not shown) can be permanently covered up orselectively covered up so that the same reactor can decant the liquid toforce mainly solids through the oxidation reaction process, or can forceboth liquids or solids (preferably in a slurry form) through thereaction zone. Each has its benefits for different kinds of sludgematerial, and can be selected as desired. FIG. 25 is a flow chart of thebasic steps involved in the process of closing or keeping open theliquid exits 366.

[0143] Another benefit of the current invention is that the inlet sludgeis subject to a gradually increasing pressure gradient when entering thereaction zone, and a decreasing pressure gradient when exiting from thereaction zone to ambient pressure through the outlet aperture 314. Thepressure drop from the reaction zone to ambient pressure in the outletaperture 314 facilitates in flushing the reaction products through thecenter tube 330 and out of the centrifuge 300.

[0144]FIG. 20 shows another embodiment of the centrifuge structure 400as modified for use as an oxidation reactor. Primarily, the main bodystructure 402 and arm structure 404 are identical to the previousembodiment described above (although the arms 404 are relatively shorterthan in the previous embodiment). The primary distinction is that theend caps are replaced with elongated tubes 406 having rounded ends 408to create a longer reaction chamber region 410. In this embodiment, theinner tube 412 extends to a position adjacent the outer end 414 of theelongated end cap tube 406, and is inside the reaction chamber 416. Asheath 418 is formed about the inner tube 412 and extends toapproximately one-half or three-quarters the length of the inner tube412 and terminates about the mid-point of the end cap tube 406. An innerannular space 422 is also formed between the intermediate tube 424 andthe sheath 418, which forms a part of the sludge input path 446. Thesheath 418 forms an annular space 420 around the inner tube 412, theannular space 420 being very small compared to the annular space 422formed between the intermediate tube 424 and the inner tube 412 (orsheath 418). The annular space 420 formed around the inner tube 412 bythe sheath 418 is part of the oxidant inlet flow path 426 for theaddition of oxidant to the inlet sludge material. The distal end 428 ofthe sheath 418 is perforated on its perimeter 430 to allow the oxidantto mix with the inlet sludge as it passes by the sheath 418 as it movesalong the inner tube 412 towards the reaction zone. A small annularspace 437 is defined around the inner tube 412 and sheath 418 by the endtube 406 as they extend into the end tube 406. The intermediate tube 424extends approximately one-half the length of the inner tube 412 andterminates near the end of the arm 432, well away from the end 434 ofthe reaction chamber 416. An outer tube 436 is formed by the arm housing438. An outer annular space 440 is formed between the outer tube 436 andthe intermediate tube 424 and defines a decanted liquid exit path 442.

[0145] The oxidant inlet path 426 extends from the base 448 of anannular region 450 formed by the sheath 418, through a channel 451 inthe main body 402, and is connected to an outer annular space 452 formedon the inside 454 of an inlet pipe 456. This outer annular space 452 isformed by a tube 458 welded or connected inside the inlet path 460 tothe inner walls 454 of the inlet pipe 456. The outer annular space 452in the inlet pipe 456 is in fluid connection with an oxygen manifold 462rotatably mounted on the exterior 464 of the inlet pipe 456. Themanifold 462 is attached to an oxidant source, such as a tank or oxidantline 468. The oxidant thus flows into the oxidant manifold 462, throughthe apertures 466 formed on the wall 454 of the inlet pipe 456, and intothe outer annular region 452 of the inlet pipe 456. The oxidant flowsalong the inlet pipe 456 in the outer annular region 452 to the oxidantchannel 451 flowing through the central body 402 of the centrifuge 400to the base 448 of the annular region 450 formed between the sheath 418and the inner tube 412. The oxidant then flows along the length of theinner tube 412 to the perforated holes 430, where it then mixes with theincoming sludge to add oxidant the sludge and prepare it for theoxidation reaction.

[0146] The arms 404 of the tubes are shorter in this embodiment than inthe previous embodiments described to allow for the elongated end captube 406, with the total centrifuge 400 diameter remaining approximatelythe same. The arms 404 could be longer or shorter as desired and the endtubes 406 could be longer or shorter as desired to define the properexternal dimensions of the centrifuge 400 as well as the proper size ofreaction chamber 416. Currently, as described herein, the reactionchamber 416 or zone is approximately one-quarter to one-half of thetotal length of the arm 404 of the centrifuge 400.

[0147] The tubular end cap 406 is formed of a material, such as metal,that is sufficiently strong and resilient enough to withstand the highpressure and temperature of the oxidation reaction occurring with theend cap 406. The tubular end caps 406 are effectively bell-jar shapedwith an internal flange 470 that wedges against the semi-conical,frusti-conical end cap collar 472. The centrifugal force from spinningcauses a positive engagement between the angular flange 470 around thebottom 474 of the tubular end cap 406 and the inner wall 476 of thesemi-conical end cap collar 472.

[0148] A heating element 478 is positioned around the tubular end cap406, preferably around its entirety, about which an insulated layer 480is positioned and held in place by fasteners 482 attaching to the endcap collar 472. The heat source 478, as noted above, can be any suitableheating element. The heat source 478 can be inside the arm 404 and endcap 406 or outside the arm 404 and end cap 406, and can cover all of orpart of the arm 404 and end cap 406 surrounding the reaction zone. Forinstance, the heat source 478 could be a band formed around thecircumference of the arm 404 or end cap 406, or can be a stripeextending longitudinally along the arm 404 or end cap 406. The heatsource 478 is preferably covered by an insulating material to assist inenergy efficiency. As noted above, the heat source 478 can be turned offor otherwise controlled as needed after the oxidation reaction hasbegun.

[0149] Oxidant is added to the sludge through the oxidant source thatflows from the annulus 462 surrounding the inlet pipe 456 to the pathway450 through the central body 402, which in turn leads to the sheath 418,which forms the annular space 420 around the inner tube 412. A length ofthe sheath 418 near its distal end 428 is perforated 430 to allow theoxidant to permeate the sludge that passes over the sheath 418 as thesludge flows towards the end 434 of the reaction chamber 416 to form theplug. The sheath 418 is preferably perforated 430 around itscircumference for the oxidant to be evenly dispersed into the sludge.The amount of oxidant dispersed into the sludge depends on the pressureof the oxidant in the in-feed line 468 and the compaction level of thedewatered sludge. The level of oxidant to be diffused into the sludgedepends on which type of sludge is to be incinerated in the oxidationreaction process. The oxidant is preferably diffused into and around thesludge after it is de-watered substantially in order to efficiently usethe oxidant. If added prior to the compaction step, some of the oxidantis lost in the compaction process.

[0150] The oxidant can be inserted through injectors (not shown) placedthrough the wall 488 of the housing 438 at the desired location. Theseinjectors can be positioned as desired and needed, and can be replaced,removed and maintained. The injectors are fed oxidant by a differentsource path than that described above for the sheath 418, such as byindividual lines running to each injector. Other oxidant insertion meanscan be used also.

[0151] In FIGS. 20 and 21, the heat energy required for the oxidationreaction is generated by a heating element 478 positioned around theentirety of the external side of the reactor and tubular end cap 406.The tubular end cap 406 is preferably made of metal to conduct the heatefficiently. The heating element 478 in the instant case is anelectrical coil, but could also be any other adequate means to providethe required temperature level, such as but limited to, a radiation orother source of heat energy for this application. The electric heatingelement 478 is supplied with electricity by contacts, such as brushcontacts 496, that engage an electrically charged collar 492 near theoutlet aperture 490 of the centrifuge 400. The collar 492 at the bottom494 of the main body 402 is rotationally attached to the bottom 494 ofthe main body 402 and stays stationary with respect to the main body 402as the main body 402 rotates. The brushes 496 contact the collar 492 andthe brushes 496 rotate therearound with the centrifuge 400, to provideelectrical connection for supplying energy to the heating elements 478.Any other manner of providing the required energy for actuation of theparticular type of heating element 478 used is acceptable. As onealternative example, electromagnetic induction coils could be used(placed circumferentially around the rim) so that when the centrifuge isspun through a magnetic field the coils heat up, as is known in the art.The magnetic field is then able to be turned on, off, or adjusted tocontrol the heat applied to the reaction zone. As mentioned above, aninsulating cover (not shown) surrounds the heating element 478 to makethe heating element 478 more efficient.

[0152] In this embodiment, an auger/choke arm 500 is positioned insideeach of the inner tubes 412. The arm 500 is similar to the augersdescribed above with flighting 502 positioned at its distal end 504 tohelp draw material into the center 506 of the inner tube 412, andflighting 502 attached near the proximate end 508 of the arm 500 wherethe arm 500 attaches to the central hydraulic motor 510. The positioningof this flighting 502 can be varied depending on the particularoxidation reaction and the requisite desired output characteristics. Ata mid-portion 512 of the arm 500, a choke 514 is formed which is anenlarged region 514 of the arm 500, which takes up a majority of thespace within the inner tube 412.

[0153]FIG. 21 shows one side of the centrifuge 400 represented in FIG.20. The raw sludge or raw material flows into the centrifuge 400 throughthe entrance path 460 and then into the arm 404. If the liquids aredesired to be decanted, the liquid exit paths 442 are kept open and thedecanted liquids flow back toward the center 516 as shown in FIG. 21 toexit the centrifuge 400 as described above. The solids, which aresomewhat de-watered, move towards the end of the arm 432. The solids arecompacted as they flow into the small annular space 437 defined aroundthe inner tube 412 and sheath 418 as they extend into the end tube 406.This pinch point 518 helps de-water the sludge. The oxidant ispreferably introduced at, near or after this point 518. The sludge formsa plug at the end 434 of the reaction chamber 416. As they move down thearm, they pass along the sheath 418 and begin compaction. As thecompacted solids move along the sheath 418 over the perforations, theoxidant is dissolved into the solids and otherwise introduced into thereaction zone at the desired level for maintaining the oxidationreaction process.

[0154] The de-watered sludge then passes beyond the end 428 of thesheath 418 and contacts the inner tube 412 at which point it flows tothe end 434 of the reaction chamber 416 in its de-watered, concentratedcondition. At this location in the reaction chamber 416, thetemperature, pressure and oxygen content are all established to supportthe oxidation reaction process.

[0155] As described above, after the oxidation reaction occurs, theby-products of the oxidation reaction process are initially augured outby the central auger 500 down the inner tube 412 towards the main body402 of the centrifuge 400. The flighting 502 at the distal end 504 ofthe auger 500 helps the reaction by-products begin the path towardsexiting the centrifuge 400. Flighting 502 at the proximate end 508 ofthe auger 500 helps push the waste products out the exit aperture 490.

[0156] The choke 514 formed along the central part 512 of the auger 500controls the pressure of the reaction chamber 416, that is, it maintainsthe pressure in the reaction chamber 416 to control the flash of thepressurized water to steam as it exits past the choke 514. The choke 514is mainly an enlarged portion 512 of the auger 500 that consumes thevolume of the space inside the inner tube 412. The volume of the choke514 depends on the amount of control of the flashpoint of thepressurized water to steam as is desired. The choke 514 can take manyforms, such as that shown, being an area of increased diameter withgradual front 520 and rear 522 edges, or it can be an area of increaseddiameter with abrupt front and rear edges, such as a disk mountedtransversely inside the inner tube 412. The shape and position of thechoke 514 depends on the pressure to be controlled and the physicalcharacteristics of the “flash to steam” process. The choke 514 can havegrooves formed longitudinally therein, or other such features, as anadditional manner to help control the pressure on either side of thechoke 514.

[0157] The augers 500 are driven in the inner tube 412 by the hydraulicmotor 510 positioned in the center 516 of the main body 402, as isdescribed above. The auger 500 is driven by a hydraulic motor 510, whichdrives the auger 500 at a selected speed independent of the spin speedof the centrifuge 400. The hydraulic motor 510 is driven by pressurizedhydraulic fluid and is fed by a separate shaft 524 inserted into themain body 402 from the end 526 opposite the inlet channel 460.

[0158] The heat transfer from the inner annular space 422 to the inside528 of the inner tube 412 is (through the wall 530 of the inner tube 412or the combination of the sheath 418 and the inner tube 412) ispreferably minimized. The sheath 418, if used, helps provide aninsulating layer. Otherwise some sort of insulation is used on the innertube walls 530.

[0159] As in the embodiment described above, the end cap collar 472 isheld in place by bolts 532 that when tightened pull the entire arm 404towards the main body 402.

[0160]FIGS. 22, 23 and 24 show another embodiment of the centrifuge 600of the present invention for use as a supercritical oxidation reactor.FIG. 22 shows the centrifuge 600 of the present invention having a mainbody structure 602 and arm structure 604 very similar to the embodimentdescribed with respect to FIGS. 20 and 21. In this embodiment, however,the inner tube 606 has a variety of shapes as it extends from the mainbody 602 of the centrifuge 600 to the distal end 608 of the arm 604. Theinner tube 606 has a first length defining a cone 610 starting from alarge diameter 612 attached to this main body 602 to a relativelysmaller diameter 614. The inner tube 606 then transitions to a length ofa cylindrical shape 616 having a constant diameter along the middlethird 618 of its length. The tube 606 at the distal end 620 transitionsfrom the cylindrical tube shape 616 to a cone 610 having a decreasingdiameter to a fixed length that is cylindrical 620 and which is open.Each region is approximately one-third the length of the inner tube 606or less.

[0161] In this embodiment, the oxidant is inserted by injectors 622 atthe inner end 624 of the tubular end cap 626, near the end cap collar628.

[0162] The auger 500, extending into each of the arms 604 inside theinner tubes 606 in the previous embodiment, is replaced by a waterdispersion probe 630 having a hollow shape for carrying water. The waterdispersion probe 630 extends at least partially into the inner tube 606and extends towards the distal end 620. The probe 630 is provided withwater through a piping system, one version of which is shown in FIG. 22.The probe 630 can be a continuous hollow pipe extending in eitherdirection into each inner tube 606. The probe 630 can also be separatefor each arm 604 and adjustable along the length of the inner tube 606individually in each arm 604 by any known mechanical means for allowingsuch adjustment. Alternatively, the probe 630 can have a fixed lengthbut float between the opposing arms 604 to the extent necessary based onthe pressure of the oxidation reaction on the tip 631 of the probe 630.Other approximate cooling liquids could be used instead of water.

[0163] The probe 630 is a hollow tube with a curved spray end 634 havingapertures 636 formed adjacent the end 634 for spraying water into theinner tube 606. The water acts as a coolant for helping control thetemperature of the reaction by-products in the inner tube 606 as theyflow towards the exit aperture 638, near the location of the flash pointbetween the pressurized water and the steam. The curved end 634 of theprobe 630 is an enlarged tip 631 which also acts as a choke (asdescribed above) to help physically control the pressure as well as theresultant velocity of the reaction by-product as it passes the choke 631towards the exit aperture 638. The water exits the probe 630 throughapertures 636 formed adjacent the head 634 of the probe 630.

[0164] The centrifuge 600 in FIG. 22 is shown suspended to rotate alonga vertical axis 640, causing the arms 604 to rotate through a horizontalaxis 640 (see FIG. 24). The centrifuge 600 is supported by rotationalbearings 642 holding onto the inlet pipe 644. The rotational bearings642 are supported by a frame 646 which suspends the entire centrifuge600. The arms 604 of the centrifuge 600 spin within the top portion 648of a housing 650, thus helping keep any external object from interferingwith the motion of the rotating arms 604. The exit aperture portion 638of the housing 650 is rotatably attached to a collar 652. The collar 652exits into a closed chamber 654. The closed chamber 654 has opposingsidewalls 656, a top wall 658 fixed to the sidewalls 656 and to thecircumference or perimeter of the collar 652, and a bottom wall 662. Thebottom wall 662 can consist of opposing sloped walls 664 and ahorizontally positioned flat wall 666 extending between the bases 668 ofthe opposing sloped walls 664.

[0165] The closed chamber 654 is intended to hold a liquid, such aswater, which acts as a heat sink for the reaction by-products exitingthe centrifuge 600. The chamber 654 has at least one outlet 670 for thewater positioned on the sidewalls 656. The chamber 654 also has at leastone outlet 672 for the reaction by-products that settle to the bottom662 of the chamber 654 for removal therefrom. The water supply line 632for the probes 630 can pass through the sidewall 656 of the chamber 654and attach to the bottom 674 of a water inlet feed 676 for the probe630. The top of the water inlet feed 676 for the probe 630 is attachedto the probe 630 in a fluid connection to allow the probe 630 to supplywater into the inner tubes 606 as desired, for each of the instanceswhere the probe 630 is stationary, the probe 630 is floating, or theprobes 630 are independently adjustable within each arm 604.

[0166] A gas volume 678 is positioned between the top surface 680 of thewater 681 and the cover 682 of the closed chamber 654. At least one gasinlet aperture 684 is formed in the sidewall 656 of the chamber 654 toallow gas to be added to or removed from that volume 678. The gasaperture 684 can be left to the atmosphere if desired. The pressure inthe system can be affected by the water level on the collar 652. As thewater level is raised, the back pressure on the system is increased, andas the water level is decreased in the chamber 654, the back pressure onthe system is decreased. All the gas can be removed from the chamber 654and replaced with water to maximize the back pressure adjustment.Additional water head pressure can be created by extending the chamber654 to surround the frame 646 up along the sides 686 of the centrifuge600 if so desired.

[0167] The collar 652 to which the centrifuge 600 is attached can berigidly attached to the centrifuge 600 in order to spin in the water. Inthis instance, the cover 682 of the closed chamber 654 is sealingly yetrotatably engaged to the circumference of the collar 652. The spinningof the collar 652 can actuate the water and create a vortex which inturn can further assist in drawing the by-products from the outlet 672and also helps mix the by-products with the water.

[0168]FIG. 23 is an enlarged view of one arm 604 of the centrifuge 600of the embodiment shown in FIG. 22, and shows the head 634 of the probe630 at different positions along the length of the inner tube 606.

[0169] The back pressure particular to each arm 604 and acting on theoxidation reaction zone, is affected by the position of the probe 630along the inner tube 606. Thus the adjustment of each of the probes 630within each of the tubes 606 respectively is an option that is helpfulfor fine tuning the oxidation reaction in each of the arms 604.Alternatively, with the “floating” probe 630, the probe 630 canself-adjust based on the pressure in each arm 604, with the arm 604having the higher pressure pushing the probe 630 towards the other arm604 to the point where the pressures are balanced at the opposing heads634 of the floating probe 630. The oxidation reaction can be halted bymoving the probe 630 away from the reaction zone and towards the mainbody 602 a sufficient amount to allow the pressure to drop below thecritical pressure.

[0170]FIG. 24 shows the frame 646 used to suspend the centrifuge 600 ina tank 690. The motor 692 for spinning the centrifuge 600 is shown witha belt 694 attaching the motor 692 to the shaft 696 of the centrifuge600. The braking mechanism 698 for the centrifuge is best shown in FIG.24. It consists of a series of brake disks 698 (three are shown)attached concentrically to the input shaft 696. A brake caliper 700 isattached to the frame 646 and is positioned on each disk 698. The brakecalipers 700 are used to engage the respective disks 698 either togetheror individually to stop the rotation of the centrifuge 600 as desired.The brake system 698 shown is one means of slowing and stopping thecentrifuge 600, and can do so in approximately 30 seconds.

[0171] The frame 646 is shown having five outwardly and downwardlyextending legs 702 each attached at their bottom 704 to a base frame706, and attached at their tops 708 together to support the centrifuge600 by its shaft 696. One side 710 of the frame 646 is open with no legs702 to allow the centrifuge 600 to be positioned in and removed from theframe 646.

[0172]FIG. 25 is a flow chart depicting the steps involved indetermining the handling of different types of input material. Inparticular, FIG. 24 addresses the inclusion or exclusion of thedecanting step and the treatment of the input material. The processbegins at Step X where the input material is analyzed to determine whattype of material it is and how it should be processed, which occurs atStep Y. If the material is solids and liquids, the next operation is toensure that the liquid exits are open in order to allow the de-wateredsolids to move to the reaction zone for becoming part of the oxidationreaction after which the reaction waste products exit the centrifuge.With the liquid exits open, the decanted liquid can exit the centrifugewithout going through the reaction zone. If the type of material to beprocessed is mainly solids, the liquid exits are closed and all of theinput material flows to the reaction zone to be part of the oxidationreaction. The oxidation reaction waste by-products then flow to the exitof the centrifuge.

[0173] The instant invention as used as an oxidation reactor providesseveral benefit as listed below.

[0174] 1. Wet oxidation of subcritical and supercritical conditions ispossible, based on the physical parameters required for the particularoxidation process (e.g. pressure, temperature, and oxidant content).

[0175] 2. Centrifuge allows control of sludge feed density by theinitial de-watering of sludge, if desired, or by the linking of two ormore centrifuges together to obtain the proper moisture content in thesludge for the oxidation reaction process.

[0176] 3. The user of the centrifuge combines the thickening process andthe de-watering process with wet oxidation reaction.

[0177] 4. This invention eliminates the need for upstream pressurizationand downstream depressurization of the influent and the effluent,respectively, and the associated mechanical equipment. This is becausethe inlet and outlet of the centrifuge can both be at ambient pressure.It is possible that the inlet might be at an increased pressure due tothe pumping of the material into the centrifuge.

[0178] 5. There is greater safety affiliated with this system because ofthe relatively low pressure inlet fee and outlet feed.

[0179] 6. The internal conditions of the reaction zone can be controlledby the speed of rotation, the inlet feed, the amount of heat energyapplied, and the applied oxygen level. This control is relatively simplecompared to the other supercritical oxidation reactor structures.

[0180] 7. There is a relatively gradual increase of pressure on thematerial to be oxidized as it flows from the inlet to the reaction zone.

[0181] 8. The mechanical design of the centrifuge allows replacement ofmaintenance wear items, i.e., the reaction chamber could be removed fromthe end of the arms by removing the end cap; and the inner tube, theintermediate tube and the outer tube all can be replaced individually asneeded.

[0182] 9. The centrifuge provides hydrostatic head on oxygen feedthereby eliminating the need for high pressure oxygen feed pump.

[0183] 10. The centrifuge has a relatively low cost to operate.

[0184] 11. There is a lower capital cost affiliated with this apparatusdue to the large reduction in equipment, for instance, there is norequirement for specialized high pressure equipment upstream ordownstream of the reaction.

[0185] 12. There is likely an improved efficiency in the reactionprocess in this environment.

[0186] 13. The centrifuge is extremely portable and easy to transportand can be taken to the site where the input material is created or moreconveniently accessed.

[0187] 14. The pressure gradient allows the sludge to move fromsubcritical to supercritical (i.e., the reaction process transitionsfrom subcritical to supercritical oxidation reaction allowing moreretention time in the reaction zone). The pressure gradient, as thesludge moves outwardly along the arm, starts at a subcritical oxidationreaction level and transitions to a supercritical oxidation reactionlevel.

[0188] The oxidation reactor of the present invention can treat wastehaving a more solid form, such as sewage sludge, where liquid can beneutralized by other means. It can also handle waste in liquid ormixed-liquid form, such as animal waste—where all material, solid andliquid needs to be processed in a centrifugal machine modified to blockthe liquid exit. This would allow one tube to be removed, and mightrequire adjustment of the reaction chamber size.

[0189] The term gas as used herein is intended to include all phases ofa material, including but not limited to, liquid, compressed gas, or lowpressure gas. While oxygen is specifically mentioned as an oxidant, itis not exclusive, and any other gas that is useful in subcritical orsupercritical oxidation reactions is sufficient.

[0190] While the invention has been particularly shown and describedwith reference to preferred embodiments thereof, it will be understoodby those skilled in the art that various other changes in structuralform and detail may be made without departing from the spirit and scopeof the invention.

[0191] Presently preferred embodiments of the present invention and manyof its improvements have been described with a degree of particularity.It should be understood that this description has been made by way ofexample, and that the invention is defined by the scope of the followingclaims.

What is claimed is:
 1. A method of using a centrifuge to separate alight material that is within an input mixture from a heavy materialthat is within the input mixture, while at the same time independentlycontrolling a speed of rotation of the centrifuge and a speed of removalof the heavy material from the centrifuge, comprising the steps of:providing a first and a second arm assembly aligned on an arm-axis andthat are rotatable in a plane extending generally perpendicular to arotation-axis; providing that each of said first and second armassemblies includes a tubular-housing having a closed outer end, anintermediate tube having an open outer end, and an inner tube having anopen outer end; providing that said inner tube of each arm assembly isof a given length; providing that said intermediate tube of each armassembly is of a length that is less than said given length; providingthat an outer end of said tubular-housing of each arm assembly is spacedfrom said outer end of said intermediate tube and from said outer end ofsaid inner tube; providing an input mixture flow path that communicateswith a cylindrical space between said intermediate tube and said innertube of each arm assembly; providing a heavy material flow path thatcommunicates with a space within said inner tube of each arm assembly;providing a light material flow path that communicates with acylindrical space between said intermediate tube and saidtubular-housing of each arm assembly; providing a conveyer screw withinthe inner tube of each arm assembly; providing first speed controllabledrive means connected to effect rotation of said first and second armassemblies about said rotation-axis; and providing second speedcontrollable drive means connected to effect rotation of said conveyerscrews.
 2. The method of claim 1 wherein said first speed-controllabledrive means is an electric motor and wherein said secondspeed-controllable drive means is a hydraulic motor.
 3. The method ofclaim 2 wherein said rotation-axis extends in a horizontal direction. 4.In a centrifuge wherein a light material within an input mixture isseparated from a heavy material within the input mixture, the centrifugeincluding a first and a second axially aligned arm assembly rotatable ina plane that extends generally perpendicular to an axis of rotation,wherein each of the first and second arm assemblies includes atubular-housing having a closed outer end, an intermediate tube havingan open outer end, and an inner tube having an open outer end, whereinthe inner tube of each arm assembly is of a given length, wherein theintermediate tube of each arm assembly is of a length that is less thanthe inner tube, wherein the outer end of the tubular-housing of each armassembly is spaced from the outer end of the intermediate tube and fromthe outer end of the inner tube, wherein an input mixtureinput-flow-path communicates with a space between the intermediate tubeand the inner tube of each arm assembly, wherein a heavy materialoutput-flow-path communicates with a space within the inner tube of eacharm assembly, and wherein a light material output-flow-path communicateswith a space between the intermediate tube and the tubular-housing ofeach arm assembly, a method of mounting the inner ends of thetubular-housing, the intermediate tube and the inner tube of each armassembly to a central member that rotates about the axis of rotation,comprising the steps of: securing the inner end of the tubular-housingof each arm assembly to opposite sides of the central member, providinga first mounting ring on the inner end of the tubular housing of eacharm assembly, the first mounting ring having an inward-facing portion;providing a second mounting ring on an inner end of the intermediatetube of each arm assembly, the second mounting ring having aninward-facing portion, and the second mounting ring having an outwardfacing portion secured to the inward-facing portion of the firstmounting ring; and providing a third mounting ring on an inner end ofthe inner tube of each arm assembly, the third mounting ring having aninward-facing portion secured to the outward-facing portion of thesecond mounting ring.
 5. The method of claim 4 wherein and the outwardfacing portion of the second mounting ring physically underlies theinward-facing portion of the first mounting ring, and wherein theoutward-facing portion of the second mounting ring overlies theinward-facing portion of the third mounting ring.
 6. The method of claim5 wherein the axis of rotation is a horizontal axis.
 7. A system foroxidizing materials, said system comprising: an entry zone; a thickeningzone; a reaction zone; a cooling zone; and an exit zone.
 8. The systemin claim 7, wherein: said entry zone is contained in a centrifugeinfluent manifold in a portion of a centrifuge arm adjacent to saidinfluent manifold.
 9. The system in claim 7, wherein: said reaction zoneis contained in an outer chamber of a centrifuge arm.
 10. The system inclaim 7, wherein: said cooling zone is contained in a center channel ofa centrifuge arm.
 11. The system in claim 7, wherein: said exit zone iscontained in an effluent manifold in a centrifuge.
 12. The system inclaim 9, wherein: a cooling tube injects cooling water into saidreaction zone.
 13. The system in claim 12, wherein: said cooling tubecan be manually adjusted along the length of said centrifuge arm. 14.The system in claim 12, wherein: said cooling tube automatically adjustsin relation to the pressures within said cooling zone.
 15. The system inclaim 7, wherein: an oxidant is injected into said reaction zone. 16.The system in claim 7, wherein: a centrate flows out of said thickeningzone.
 17. A method for oxidizing materials, said method comprising thefollowing steps providing an influent material; passing said influentmaterial through an entry zone; passing said influent material through areaction zone; passing said influent material through a cooling zone;and passing said influent material through an exit zone.
 18. The methodin claim 17, wherein: said entry zone is contained in a centrifugeinfluent manifold in a portion of a centrifuge arm adjacent to saidinfluent manifold.
 19. The method in claim 17, wherein: said reactionzone is contained in an outer chamber of a centrifuge arm.
 20. Themethod in claim 17, wherein: said cooling zone is contained in a centerchannel of a centrifuge arm.
 21. The method in claim 17, wherein: saidexit zone is contained in an effluent manifold in a centrifuge.
 22. Themethod in claim 19, wherein: a cooling tube injects cooling water intosaid reaction zone.
 23. The method in claim 22, wherein: said coolingtube can be manually adjusted along the length of said centrifuge arm.24. The method in claim 22, wherein: said cooling tube automaticallyadjusts in relation to the pressures within said cooling zone.
 25. Thesystem in claim 22, wherein: an oxidant is injected into said reactionzone.
 26. The system in claim 22, wherein: a centrate flows out of saidthickening zone.
 27. An oxidation reactor for processing an incomingmaterial, said reactor comprising: a main body having at least one inletand at least one outlet and being rotatable about an axis; at least onehollow arm extending from said main body, said arm having a distal endand a proximal end, said arm defining at least an interior inlet flowpath communicating with and leading from said inlet at said proximal endoutwardly to said distal end, and at least a first exit flow pathleading from said distal end to said proximal end and communicating withsaid outlet, and a heat source at said distal end; and a reactor regionformed at said distal end of said arm.
 28. An oxidation reactor asdefined in claim 27, further comprising a flow path for inserting anoxidant into to said reactor region.
 29. An oxidation reactor as definedin claim 27, further comprising: a second exit flow path leading to asecond outlet; said first exit flow path for the flow of the incomingmaterial after passing through said reactor region; said second exitflow path for liquid separated from the incoming material.
 30. Anoxidation reactor as defined in claim 28, wherein: said second outlet isclosed.
 31. An oxidation reactor as defined in claim 27, wherein: saidheat source is an electrode.
 32. An oxidation reactor as defined inclaim 27, wherein: said heat source is a resistive heat element.
 33. Anoxidation reactor as defined in claim 27, wherein said heat source is anelectro-magnetic heat source.
 34. An oxidation reactor as defined inclaim 27, wherein: said heat source is capable of heating the reactorregion to a temperature of approximately 705 degrees F.
 35. An oxidationreactor as defined in claim 27, wherein said distal end is formed by atubular end cap which encompasses the reactor region.
 36. An oxidationreactor as defined in claim 35 wherein said heat source at least in partsurrounds said end cap.
 37. An oxidation reactor as defined in claim 28,wherein said oxidant flow path outputs into to said reactor zone.
 38. Anoxidation reactor as defined in claim 37, wherein said oxidant flow pathincludes at least one separate injectors positioned in the outer wall ofsaid arm.
 39. An oxidation reactor as defined in claim 37, wherein saidoxidant flow path extends interior to said arm to output into saidreactor region.
 40. An oxidation reactor as defined in claim 27, furthercomprising an auger positioned in said first exit path.
 41. An oxidationreactor as defined in claim 40, wherein said auger forms a choke alongits length to assist in controlling the pressure in said reactor region.42. An oxidation reactor as defined in claim 27, further comprising aprobe positioned in said first exit flow path.
 43. An oxidation reactoras defined in claim 42, wherein said probe defines a choke along itslength to assist in controlling a pressure in said reactor region. 44.An oxidation reactor as defined in claim 43, wherein said probe isadjustable along the length of said first exit flow path.
 45. Anoxidation reactor as defined in claim 42, wherein said probe is a fluidconduit and defines at least one outlet aperture adjacent one end. 46.An oxidation reactor as defined in claim 40, wherein said probe is afluid conduit and defines at least one outlet aperture adjacent saidchoke.
 47. An oxidation reactor as defined in claim 43, wherein saidchoke is an enlarged portion formed on a distal end of said probe. 48.An oxidation reactor as defined in claim 27, wherein said outlet is intoa fluid.
 49. An oxidation reactor as defined in claim 27, wherein saidoutlet is into a fluid in a closed container.
 50. An oxidation reactoras defined in claim 49, wherein a fluid level of said fluid in saidcontainer affects a back pressure applied to said reactor region.
 51. Anoxidation reactor as defined in claim 49, wherein said closed containerincludes a gas layer above said fluid.
 52. An oxidation reactor asdefined in claim 50, wherein said fluid level can be adjusted in saidcontainer to increase or decrease a back pressure on said reaction zone.53. An oxidation reactor as defined in claim 27, wherein said main bodyrotates about a vertical axis.
 54. An oxidation reactor as defined inclaim 53, further comprising a frame for suspending said main body in amanner to allow said main body to rotate about said vertical axis. 55.An oxidation reactor as defined in claim 54, further comprising a tankmounted to the bottom of said frame, into which said outlet extends. 56.An oxidation reactor for processing an incoming material, said reactorcomprising: a main body having at least one inlet and at least oneoutlet and being rotatable about an axis; at least two opposing hollowarms extending from said main body, each of said arms having a distalend and a proximal end, said arm defining at least an interior inletflow path communicating with and leading from said inlet at saidproximal end outwardly to said distal end, and at least a first exitflow path leading from said distal end to said proximal end andcommunicating with said outlet, and a heat source at said distal end;and a reactor region formed at said distal end of each of said arms. 57.A rotating centrifuge for performing an oxidation reaction on a sludge,the centrifuge comprising: a housing having a central body and a hollowarm extending from said body, said arm having a first end attached tosaid central body, and a second end extending away from said centralbody, and an end cap attached to said second end of said arm to form achamber in said arm, said distal end of said chamber being selectivelyheated; a baffle attached to said body and extending into said chamber,said baffle having a longer inner tube having an interior and a distalend, and a shorter outer tube, said longer tube positioned inside saidshorter tube and defining an inner space therebetween; an outer spacedefined between said shorter tube and said hollow arm; an entrance pathfor the mixture of initial material formed in said housing andcommunicating with said inner space; a gas inlet channel in thecentrifuge to diffuse gas into the heavier material; an exit path forsaid light material formed in said housing and communicating with saidouter space; an exit path for said heavier material formed in saidhousing and including the interior of said longer tube; and wherein aplug is formed in said chamber adjacent said end cap to engage saiddistal end of said longer tube and thereby define a flow path to guidesaid lighter material to said exit path for said lighter material, andsaid heat and combustible gas combining with the pressure on saidheavier material to cause a oxidation reaction to occur.
 58. Anoxidation reactor for processing waste products comprising: a centrifugehaving a heated portion forming a reaction zone; and a gas inlet to mixa gas with the waste product.
 59. An oxidation reactor as defined inclaim 58, wherein: said centrifuge includes a housing having a centralbody and a hollow arm extending from said body, said arm having a firstend attached to said central body, and a second end extending away fromsaid central body, and an end cap attached to said second end of saidarm to form a chamber in said arm, said distal end of said chamber beingselectively heated to form the reaction chamber.
 60. An oxidationreactor as defined in claim 59, further comprising: a baffle attached tosaid body and extending into said chamber, said baffle having a longerinner tube having an interior and a distal end, and a shorter outertube, said longer tube positioned inside said shorter tube and definingan inner space therebetween; an outer space defined between said shortertube and said hollow arm; an entrance path for the mixture of initialmaterial formed in said housing and communicating with said inner space;a gas inlet channel in the centrifuge to diffuse gas into the heaviermaterial; an exit path for said light material formed in said housingand communicating with said outer space; and an exit path for saidheavier material formed in said housing and including the interior ofsaid longer tube.